Ok, sorry it took me a good 5 days to do this...it was actually ready much earlier. It's only been semi-tested though.
http://www.mediafire.com/?ewl3htoav1qNOTE: This is a CLIENT and SERVER mod. So you can only use it properly if you have the mod yourself and are on a server that is running it.
Instructions:
1. Unzip to Blockland folder.
2. Start up BL, go to options --> controls.
3. Set up the key for Decollision Mode, near the bottom.
4. Start a server with HotKeyServer enabled.
5. Hold down the key you set in options earlier and place a brick; you will notice that it is decollisioned.
6. Continue testing it if you like, you'll find that if you place a brick while holding down the button always decollisions the brick.
7. I also added a last-minute toggle: /togglehotkeys. Admin only, it toggles the Hot Keys so no one can use them.
Hope you like it. The on-screen notification (from when you hold the key, a picture pops up to tell you that your holding it down. It was created by Kaphix, and it took him maybe a minute or so to do. If you have something you think is better, let me know and I'll see if it works well. Target size: 100 x 100)