While I'm sure it is possible overall, the HillStart Assist feature was introduced
from the '09 models w/all trannys & newer.
The main question is what wiring harness connectors, fuse/TIPM/ECU differences would
you have to look for . If there aren't concessions for those it might be a bit more of a challenge than just "adding" it.
fwiw, I've not heard of anyone doing so a but anything can be achieved if the drive & funding is strong enough ...
I'm with Jeffery. I disabled that function with the steering wheel dance. It might be useful on truly steep trails. But the majority of the time it will be used while at a red light. It will wear your brakes down faster as well, something to think about.
I think everyone who drives should be able to use a manual transmission, no offense. It is not any harder than pedaling a bicycle while steering ...but, at least as far as a Jeep crawling off-road , the automatic will be preferable in the good rock