[SalesForce] Custom ‘Save & New’- Button with redirect to record type selection page

My custom object has different record types and an overwritten edit page.

I want to implement a 'Save & New'- Button on this VF page which redirects my users to the record type selection page.
How can I implement this in my controller extension of the VF page?

Edit:
I tried to implement the solution from DavinC. First it worked fine, but since Summer '14 it redirects me to the Record Type Selector and if I choose a Record Type and press Continue nothing happens.

VF page button:

<apex:commandButton value="Save & New" action="{!doSaveAndNew}"/>

Controller Extension method:

public PageReference doSaveAndNew() {
        PageReference result = null;        

        try {  
            upsert myObject;
            String myObjectEntityId = CustomSettings__c.getAll().values().get(0).txt_myObjectEntityId__c;
            result = new PageReference('/setup/ui/recordtypeselect.jsp?ent=' + myObjectEntityId + '+&retURL=myObjectEditPage&save_new_??url=' + myObjectEntityId + '/e');        
        } 
        catch(Exception ignore) {}

        return result;
    }

Best Answer

Take a look at the URL for the recordtype selection page for the object in question. For Opportunity for example, it's:

/setup/ui/recordtypeselect.jsp?ent=Opportunity&retURL=<VF_page>&save_new_url=006/e

006/e being the standard Opportunity edit page.

It should be a similar approach for all objects.