I'm not sure it's possible because of how the immobilizer works on T7. The reverse lock-out is not a problem, you can remove that. It's been done for turbo timers.
The main issue would be the fact that when you start the car, it looks for the chip in the key to see if the key was married to the car. I'm not sure if there is a way to jerry-rig a chip that is permanently in the car, but that would make the car much more vulnerable. As these cars are set up now stock, I don't think there is any way to start it unless you have a key.
If the reverse gear lock out can be removed, then the rest would be easy, they do it on many other cars with chips in the keys.
Basically they use a dummy key holder, something like the ignition barrel that will read the code from a spare key hidden with the barrel, when needed to start the car remotely.
The problem with the stick shift requires an "exit" procedure so you will be able to start it remotely.
Basically you park, pull up the hand brake, leave it in Neutral, press the remote start on your remote, now you remove the key from ignition (car still running), exit the car and hit the alarm "on" key on your remote.
This now shut down the car and it is ready to be restarted with the remote.
Word of advice, get integrated systems that include remote starter and alarm function all in one, in the early years of car starters, to communicate with separate alarm systems required relays and a mess of wiring and half the time it didn't work properly, one of my friends went through that s**t.
I had it on my 9000 manual, worked great for many many years, but I haven't considered it on the 9-5 because of the reverse lock-out.
I don't think it's worth messing with it either when you have working heated seats front and back, plus the cars warm up pretty quickly.