so messing around I pulled the Live instrument "External Instrument" and selected "sp-555" as the output. BAM. the piano roll now controls ALL your pads and they are fully velocity sensitive.
make sure that in the midi pref you have sp555 selected as both input and output on the lower halve where it says "input track sync output" and all that jazz
then to record the madness make a new audio track with input "ext in" (thats the default) and turn up the internal processing level on the sp 555 (cancel + start/end/level + ctrl 3 knob)
this is going to make for some interesting live sessions
test
http://www.box.net/shared/xu82ovfj0t
nothing you hear is ableton effects or samples. just ableton controlling 555 and effects from effect memory