2001 GMC Jimmy Keyless entry problems...

I have a 2001 GMC Jimmy. It did not come with Factory keyless entry.

I have put the RKE module on the hush plate & connected it to the exisitng wire harness where it belongs. I was told to take it to the dealer and have them flash the BCM and put in the RPO code to activate the keyless entry.

So I went to the dealer today and after 2 hours and $95 dollars they said that you can't add keyless entry if it didn't come from the factory. Which is a load of crap.

To make a long story short I need to know how to get the BCM into program mode so I can program the remotes...I have tried holding the unlock button down and turning the car on/off/on/off but that didn't work....

I need help anyone know how I can do it?

Thanks!

-Steve