It is possible. Here is the way i would do it
As long as you are walking if anyone or thing such as a person or closed door gets in the way this will automatically open/push them.
//Burgo's Automatic Push Script
seta PushOn "+forward; +activate"
seta PushOff "-forward; -activate"
bind W "+vstr PushOn PushOff"
You could however change:
+forward to +attack
-forward to -attack
bind W to bind MOUSE1
So it will only automatically push if someone is in the road when you are shooting. But i do not see how that is as handy as compared to being able to push whenever your walking. This way it works at your spawn, and at doors etc.
I am not a fan of hacks. I do however love programming and love scripting in ET.