First, go to system preferences > Universal Access, and make sure "Enable access for assistive devices" is checked. Next, if you haven't already, download the latest version of MidiPipe (http://homepage.mac.com/nicowald/SubtleSoft/). then create a new pipe, with an input from your MIDI in device at the top, followed by an "Applescript Trigger". Paste the following script into the Trigger:
---------------------------------
on runme(message)
if (item 1 of message = 144) and (item 2 of message = 24) and (item 3 of message > 0) then
tell application "Live"
activate
end tell
tell application "System Events"
tell process "Live"
tell menu bar 1
click menu item "Undo Slot Recording" of menu "Edit"
end tell
end tell
end tell
end if
end runme
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Line 2 in the script is your filter , selecting which MIDI note will be your remote command to delete last clip. Item 1 should stay at 144, as this tells the script to look for a note on/off message. item 2 is set to 24, which is the note number for C0. you can adjust this to any note you like. Item 3 >0 just means make sure the note has any positive velocity value, though i always set note velocities to 127 when using for Remote purposes in Live. Check "pass through" in the options. Save the script. Obviously, to make this work, you'll need to have MidiPipe booted as well as Live whenever you play. Go into Live, go to preferences > midi/sync, and under Remote Control, add ""MidiPipe Output 1" as an additional input. Now make sure you have a control on your foot controller (or whatever) programmed to the same MIDI note as you typed into "item 2 of message" in line 2 of the script. Go back into MidiPipe and press this controller once, and if everything's been entered correctly, the "not compiled" message should change to "compiled. That's it.
Now, when you go into record on a clip, and you decide that you've fucked up and need to record over, press your record pedal again to go into "play wait" (triangle flashing) mode. unfortunately, you will have to wait until the next quantize cycle (as is clear from the script, what it's actually doing is telling Live to "Undo Slot Recording" and that menu item is not available till the recording is finished) and the little triangle in the clip is solid, so it's a little slower than it needs to be, but i think it will get me through until the Abletons program something better into the actual program (which I'm sure they will
Thanks again to Charlie Roberts, for giving me his script...
enjoy
malcolm