Using Live's Tap Tempo can be quite clunky and it's also not what most singer/songwriters have in mind. What if you want Live to follow your tempo, not vice versa? This is where "Relative Tap Tempo" comes in.
Relative Tap Tempo
Created specifically with singer/songwriters in mind by Tim Canfer, you can tap out the tempo on a foot pedal while recording an instrument. Provided that transport is running, it will speed up if you tap earlier than the beat and slow down if you tap later than the beat. It also provides colour feedback showing you if you're slowing down (red for late), staying on the beat (yellow) or speeding up (green for early).
Watch the Video Demo
This way for heaps more Max for Live devices & tips.