Personally I find that by the time I've got everything I need and get out of the car the timer has almost counted to 0 anyway so I then set the alarm.
I never boost it all the way home as I live in town and don't come on boost much doing 30 mph so the timer has auto-corrected to a lower count time anyway by the time I've pulled into the drive, opened the garage, driven in, removed phone - jacket - stereo, fitted steering lock, blah, blah, shut garage door.

I'm pretty sure some clifford alarms have turbo timer functions built in so it will set the alarm as well whilst the timer counts down, but you'd have to do some research into which ones. Unless your boosting your car to your front door there won't be much time betwen you sorting yourself out and the ignition being killed.