I would basically like to do the same thing but my Sales_Rep field is in a different application.I was trying to do something like below but it doesnt let me access the other app through script but it does in look up.

I know I can stick Email == zoho.loginuserid in the lookup field criteria but then I cant change it if needed so .

Basically all i want it to do is stick the current logged in user First and last name in a created by field based on based on there name data from  a different app. I would like to modify this field in edit mode if needed so .

Thanks