A way to make PuTTY load the host with the protocol in the parameter. Supports login name and password.

putty-schema.js

var sExecutable = 'putty.exe';
var oShell = WScript.CreateObject("WScript.Shell");
var oFSO = WScript.CreateObject("Scripting.FileSystemObject");
var oFile = oFSO.GetFile(WScript.ScriptFullName);
var sExecutableFullPath = '"' + oFSO.GetParentFolderName(oFile) + "\\" + sExecutable + '"';
if(WScript.Arguments.length > 0){
  var sArg = WScript.Arguments(0);
  var aCmd = [];
  var oCmd = {
    'executable': sExecutableFullPath,
    'protocol': null,
    'login': null,
    'password': null,
    'host': null
  };
  if(sArg.indexOf('://') !== -1){
    oCmd.protocol = '-' + sArg.substr(0, sArg.indexOf('://'));
    oCmd.host = sArg.substr(sArg.indexOf('://') + 3);
  }else{
    oCmd.host = sArg;
  }
  oCmd.host = oCmd.host.replace(/\//g, '');
  if(oCmd.host.indexOf('@') !== -1){
     oCmd.login = oCmd.host.substr(0, oCmd.host.indexOf('@'));
     oCmd.host = oCmd.host.substr(oCmd.host.indexOf('@') + 1);
     if(oCmd.login.indexOf(':') !== -1){
       oCmd.password = '-pw "' + oCmd.login.substr(oCmd.login.indexOf(':') + 1) + '"';
       oCmd.login = oCmd.login.substr(0, oCmd.login.indexOf(':'));
     }
     oCmd.login = '-l "' + oCmd.login + '"';
  }
  for(var i in oCmd){
    if(oCmd[i] !== null) aCmd.push(oCmd[i]);
  }
  oShell.Run(aCmd.join(" "));
}else{
  oShell.Run(sExecutableFullPath);
}

Initially created to use with Windows registry:
HKEY_CURRENT_USER\Softwares\Classes\ssh\shell\open\command
or
HKEY_CLASSES_ROOT\ssh\shell\open\command
using the command wscript "path\to\putty-schema.js" "%1"
Just drop this script within the same directory as your putty.exe executable.

It has been designed to be flexible, just change the sExecutable property to the one needed and change the switches/options (in this case -l and -pw) to the one supported by the target executable.