An end device bind doesn’t require any code on the SmartThings side its all in the ZigBee stack. I have code but its firmware, specific to my hardware.
If you want more information on an End Device Bind take a look at section “2.4.2.2 End Device Bind Overview” on page 95 of the ZigBee Standards guide. Its a bit dry but it is the spec so your getting it straight from the horses mouth! Here is a copy of the ZigBee spec: Intranet DEIB. This PDF is not from an official ZigBee site you may want to download the official document from ZigBee.Org. You will have to fill out a little form with your information and they will send you a link but its free.