Daemontools (http://cr.yp.to/daemontools.html) run script for starting apache. Service directory basename is passed to apache via -D command line option and can be checked with <IfDefine>. For example for the script located at "/etc/service/php55/run" "php55" is defined with -D.

daemontools-run-apache.sh

#!/bin/bash
SNAME=${PWD%/*}
SNAME=${SNAME##*/}
exec 2>&1
exec \
  env -i PATH=/bin:/usr/bin PHPRC=/opt/apache-dev/servers/$SNAME \
    setuidgid www-dev \
      /opt/apache-dev/bin/httpd -D FOREGROUND -D $SNAME

httpd.conf

<IfDefine php54>
  LoadModule php5_module modules/libphp54.so
  Listen 8081
  ServerRoot /opt/apache-dev/servers/php54
</IfDefine>

<IfDefine php55>
    LoadModule php5_module modules/libphp55.so
    Listen 8082
    ServerRoot /opt/apache-dev/servers/php55
</IfDefine>