auto populate from Crm

Hey Everyone.
Ive been playing around with this for ages and cant seem to get it to work.
im trying to set up an onChange event. so that when a certain field is entered the rest of the form populates from the crm.
The issue im having is that the info i need to populate is in a custom module. so far everything ive tried fails and throws an error.
I have tried using an integration field but it wont allow me to access the custom modules.

Is there a work around for this.

Thanks
Roland