'/(keyprefix)/e?nooverride=1&RecordType={!$Request.RecordType}'

so that you can redirect to Standard New pages and it will take the selected RecordType.

This URL is called after Record Type selection, and selected RecordType is put in RecordType parameter (because you don't use URLFOR anymore, you have to put all parameters by yourself). The parameter nooverride=1 does the same thing as URLFOR(Action..., null, null, true) so that you can call original New page. You just add your field id & value pairs and other parameters (retURL, cancelURL, etc.) in the URL.

In my case, I put the routing logic in an action method (redirect()) and let it return PageReference for '/(keyprefix)/e?nooverride=1&RecordType={!$Request.RecordType}' based on given parameters.You can do the same thing with javascript document.location.

When I inherited "save_new" parameter, it still showed RecordType Selection page twice.

I hope this can help you (it worked perfect in my case).

ThomasTT

<apex:page standardController="Opportunity" extensions="OpportunityRedirectExtension" action="{!redirect}">
</apex:page>

public with sharing class OpportunityRedirectExtension {

private ApexPages.StandardController controller = null;

public OpportunityRedirectExtension (ApexPages.StandardController controller){
this.controller = controller;
}


public PageReference redirect(){

String prefix = Opportunity.SObjectType.getDescribe().getKeyPrefix();
String param = getParameters() + '&(your field id)=(your field value)';
return new PageReference('/'+prefix+'/e?nooverride=1&'+param);
}

// Inherit previous parameters, more imporatntly, RecordType parameter!
private String getParameters(){
string param = '';
Map<String, String> strMap = ApexPages.currentPage().getParameters();
String[] keys = new String[]{'RecordType', 'retURL', 'cancelURL'};
for(String s : keys){
if(strMap.containsKey(S)) param += s + '=' + strMap.get(s) + '&';
}
if(param.length() > 0) param = param.substring(0, param.length()-1);
return param;
}

}