Triggering "step-thru" loops with Roland TD-4, SPD-S, and mac possible?

[robo456]

Hey guys... I've been searching thru the forums, "googling", and youtube, but I haven't found exactly what I'm looking for. Here's my current setup:

Roland TD-4 (connected to mixer and Macbook via roland UM-1G midi interface)
Roland SPD-S (currently connected to mixer)

I use Logic 8 and the Addictive Drums package, as well as Garageband on the macbook. I have no problems using the SPD-S in wave or patch mode for triggering loops, but only in a "start/stop" or overlayering fashion. What I'd really like to be able to do is trigger a "step-thru" type loop like my friend's TD-20. I'm not sure if I'm using the right words; basically, you hit one pad and each time you hit it, it steps thru the loop, one note at a time. There's alot of videos on youtube from the NAMM events that show it, but it's always on the newer 'brains'. Here's a video of Johnny Rabb on the TD-20KX kit; perfect example is at 1:22 (melodious) and 2:10 (neotype) https://www.youtube.com/watch?v=oMF1WzRKus4#.

I really don't have the money to drop to get a new drum set, but I wouldn't be opposed to pick up ProTools, Ableton, or a similar program that might help out.

Has anyone ever tried to do this, or are there any forum posts I might have missed?

Thanks in advance for any info!!

**EDIT**
From more searching, Roland uses the term "Tap Sequencing" and from what I can tell, it was available on the TD6, 8, 12, 20, and now the 30.

I've gotten closer with looking at Ableton Live videos/guides about "slicing to MIDI" but still not quite there...

--rob