Adding a keypad to Vista 10SE alarm system

I recently bought a house with a pre-installed ADT system. System was installed in 2000. User manual says it is either a VIA-30PSE or a Vista-10SE. I believe it is the latter. It has a single 6127/6128 keypad in the house. The semi-detached garage has a motion detector. I would like to add another keypad to the garage, since getting into/out of the car/pulling in/pulling out/opening/shutting the garage door before the entry/exit delay is proving to be a bit of a push. 6128 keypads are available used on Ebay. Right now, I have that zone bypassed, but this is a pain, not only because I WANT protection out there, but also because (apparently) you have to BYPASS the zone EACH TIME re re-activate the system. I've run all kinds of wiring & am not concerned with the technical aspects of installing the keypad, but I'm wondering what keypad to get. Also, all I have is the fairly useless from a technical standpoint user manual. Is there any technical info online, as to how & where to connect a 2nd pad to the system?
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