I just gave it a go - it's a bit strange, but this will work:
1. [Learn][1][Enter]
2. Hold down [Timing Disabled], and tap the master load button
3. [Learn]
4. Go into the Macro viewer, and edit Macro 1 to only include " TimingDisable 0 █ "
This should now toggle your main playback between TD and normal.
-luke-
