These are the steps to get Nginx running alongside MAMP on a Mac.

nginx-mamp-macports.txt

# These steps will get nginx installed on your Mac for local development and
# testing purposes, to be used alongside MAMP (which already includes Apache).
# The following steps assume that you're running MAMP and that you already
# have php-cgi in /Applications/MAMP/bin/php/php5.4.10/bin/php-cgi.
# The start-nginx and stop-nginx scripts created at the end do not 
# start or stop MySQL because it is assumed that you normally run MAMP
# with Apache + MySQL turned on and that you occasionally want to switch 
# your web server to Nginx for testing purposes and that you leave MySQL running.

# This process was tested successfully on OS X 10.9.

# Now let's begin. If you don't already have it, download and install macports: 
# http://www.macports.org/install.php


$ sudo port selfupdate
$ sudo port install nginx

$ sudo mkdir /var/log/nginx
$ sudo chown root:wheel /var/log/nginx

$ cd /opt/local/etc/nginx
$ sudo mkdir sites-enabled
$ sudo mkdir global
$ sudo cp mime.types.default mime.types
$ mate fastcgi.conf # or vim fastcgi.conf


fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
fastcgi_param  QUERY_STRING       $query_string;
fastcgi_param  REQUEST_METHOD     $request_method;
fastcgi_param  CONTENT_TYPE       $content_type;
fastcgi_param  CONTENT_LENGTH     $content_length;

fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
fastcgi_param  REQUEST_URI        $request_uri;
fastcgi_param  DOCUMENT_URI       $document_uri;
fastcgi_param  DOCUMENT_ROOT      $document_root;
fastcgi_param  SERVER_PROTOCOL    $server_protocol;
fastcgi_param  HTTPS              $https if_not_empty;

fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;

fastcgi_param  REMOTE_ADDR        $remote_addr;
fastcgi_param  REMOTE_PORT        $remote_port;
fastcgi_param  SERVER_ADDR        $server_addr;
fastcgi_param  SERVER_PORT        $server_port;
fastcgi_param  SERVER_NAME        $server_name;

# PHP only, required if PHP was built with --enable-force-cgi-redirect
fastcgi_param  REDIRECT_STATUS    200;


$ mate nginx.conf # or vim nginx.conf


# Nginx Config
# Note: all Nginx config files follow the WordPress recommendations here: 
# http://codex.wordpress.org/Nginx
 
user changeme staff; # set 'changeme' to your username; root and nobody cause permissions issues
worker_processes  1;

# Make sure the /var/log/nginx/ directory exists; if not create it and chown root:wheel
error_log	/var/log/nginx/error.log;

events {
    worker_connections  1024;
}
 
http {
	
    include				mime.types;
    default_type		application/octet-stream;
    access_log			/var/log/nginx/access.log;
    sendfile        	on;
    #tcp_nopush			on;
	#gzip				on;
    keepalive_timeout	3;
	# php max upload limit cannot be larger than this
	client_max_body_size 13m;
	index				index.php index.html index.htm;
 
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';
	
	# Include per-site configuration files
	include sites-enabled/*;
}

$ mate global/restrictions.conf # or vim global/restrictions.conf


# Global restrictions configuration file.
# Designed to be included in any server {} block.</p>
location = /favicon.ico {
	log_not_found off;
	access_log off;
}

location = /robots.txt {
	allow all;
	log_not_found off;
	access_log off;
}

# Deny all attempts to access hidden files such as .htaccess, .htpasswd, .DS_Store (Mac).
# Keep logging the requests to parse later (or to pass to firewall utilities such as fail2ban)
location ~ /\. {
	deny all;
}

# Deny access to any files with a .php extension in the uploads directory
# Works in sub-directory installs and also in multisite network
# Keep logging the requests to parse later (or to pass to firewall utilities such as fail2ban)
location ~* /(?:uploads|files)/.*\.php$ {
	deny all;
}


$ mate global/wordpress.conf # or vim global/wordpress.conf


# WordPress single blog rules.
# Designed to be included in any server {} block.

# This order might seem weird - this is attempted to match last if rules below fail.
# http://wiki.nginx.org/HttpCoreModule
location / {
	try_files $uri $uri/ /index.php?$args;
}

# Add trailing slash to */wp-admin requests.
rewrite /wp-admin$ $scheme://$host$uri/ permanent;

# Directives to send expires headers and turn off 404 error logging.
location ~* ^.+\.(ogg|ogv|svg|svgz|eot|otf|woff|mp4|ttf|rss|atom|jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|ppt|tar|mid|midi|wav|bmp|rtf)$ {
       access_log off; log_not_found off; expires max;
}

# Uncomment one of the lines below for the appropriate caching plugin (if used).
#include global/wordpress-wp-super-cache.conf;
#include global/wordpress-w3-total-cache.conf;

# Pass all .php files onto a php-fpm/php-fcgi server.
location ~ \.php$ {
	# Zero-day exploit defense.
	# http://forum.nginx.org/read.php?2,88845,page=3
	# Won't work properly (404 error) if the file is not stored on this server, which is entirely possible with php-fpm/php-fcgi.
	# Comment the 'try_files' line out if you set up php-fpm/php-fcgi on another machine.  And then cross your fingers that you won't get hacked.
	try_files $uri =404;

	fastcgi_split_path_info ^(.+\.php)(/.+)$;
	#NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
	
	fastcgi_pass   127.0.0.1:9000;
    fastcgi_index  index.php;
    fastcgi_param  SCRIPT_FILENAME $fastcgi_script_name;
	fastcgi_param  PATH_INFO $fastcgi_script_name;
    include        /opt/local/etc/nginx/fastcgi.conf;
}


$ mate sites-enabled/example.dev.conf # or vim sites-enabled/example.dev.conf


# Redirect everything to the main site. We use a separate server statement and NOT an if statement - see http://wiki.nginx.org/IfIsEvil

server {
        server_name  _;
        rewrite ^ $scheme://example.dev$request_uri redirect;
}

server {
	server_name example.dev;
	root /Users/changeme/Sites/example.dev;

	include global/restrictions.conf;
	include global/wordpress.conf;
}


$ sudo mkdir /opt/local/etc/LaunchDaemons/org.mamp.php-cgi
$ cd /opt/local/etc/LaunchDaemons/org.mamp.php-cgi
$ mate org.mamp.php-cgi.plist # or vim org.mamp.php-cgi.plist


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>org.mamp.php-cgi</string>
  <key>ProgramArguments</key>
  <array>
    <string>/Applications/MAMP/bin/php/php5.4.10/bin/php-cgi</string>
    <string>-b127.0.0.1:9000</string>
    <string>-q</string>
  </array>
  <key>EnvironmentVariables</key>
  <dict>
    <key>PHP_FCGI_CHILDREN</key>
    <string>2</string>
    <key>PHP_FCGI_MAX_REQUESTS</key>
    <string>256</string>
  </dict>
  <key>Debug</key><false/>
  <key>Disabled</key><true/>
  <key>KeepAlive</key><true/>
</dict>
</plist>


$ chown root:admin /opt/local/etc/LaunchDaemons/*
$ sudo ln -s /opt/local/etc/LaunchDaemons/org.mamp.php-cgi/org.mamp.php-cgi.plist /Library/LaunchDaemons/org.mamp.php-cgi.plist

$ mate /opt/local/bin/start-nginx # or vim /opt/local/bin/start-nginx


#!/bin/bash
echo 'Stopping Apache...'
sudo /Applications/MAMP/Library/bin/apachectl stop
echo 'Starting nginx and php-cgi daemons...'
sudo launchctl load -w /Library/LaunchDaemons/org.mamp.php-cgi.plist
sudo launchctl load -w /Library/LaunchDaemons/org.macports.nginx.plist
echo 'Loading nginx configuration files from /opt/local/etc/nginx/sites-enabled/...'
\ls -1A /opt/local/etc/nginx/sites-enabled/


$ mate /opt/local/bin/stop-nginx # or vim /opt/local/bin/stop-nginx


#!/bin/bash
echo 'Stopping nginx and php-cgi daemons...'
sudo launchctl unload -w /Library/LaunchDaemons/org.mamp.php-cgi.plist
sudo launchctl unload -w /Library/LaunchDaemons/org.macports.nginx.plist
echo 'Starting Apache...'
sudo /Applications/MAMP/Library/bin/apachectl start
echo 'nginx and php-cgi are now stopped and Apache is running'

$ chmox +x /opt/local/bin/start-nginx
$ chmox +x /opt/local/bin/stop-nginx
$ start-nginx