I'm not sure you can do that straight up to work per-tool. What you can do is write a script that'll fire a command based on the currently active tool (I've got various modal tools set up this way - for example, W is bound to weld unless I'm in item mode, then it'll activate the move tool).
RESURRECTION! I'm trying to set up tool specific hot keys for the translate, rotate and scale tools but I'm having trouble as all 3 tools seem to be named "xfrm.transform". So I have something like this: <hash type="Region"…