Thats possible.
First of, you would like to know were to place it. Maybe you would like a silhouette (hmm?) on exactly the place the bomb will be placed. Make a alternate texture for it. Maybe red with 30-50% opacity.
When the player comes to walks forward to it and presses enter the bomb changes to its NORMAL 100%opacity-texture ( alttex=0, then alttex=1. I dont know if the command is like that but ill check it out later..).
At that point the bomb is armed. You can choose if you want to detonate it yourself, or if you want it to be detonated after a couple of seconds. E.g. when the timer has reached 5000 milliseconds, it explodes and activates the wall's ifused. That triggers the walls animation (implosion/explosion. Depends what side of the wall you are
). Or maybe the wall just is destroyed oand disappears.
You can apply the command triggerforce=X and set it on maybe 200 and put some crates beside it so they will fly away and simulate the forcewave of the explosion.
I also suggest that a MOD moves this thread to the scripting section, and maybe I can post you a complete script for you and everyone else that finds it useable.
www.myspace.com/sculptednoise