Apols if someone has already posted something on this. Did a search but couldn’t find anything.
I know how to get the tape to start recording on a bar marker when I start a sequencer playing (have the sequencer ready to go, hold down the record button and keep it held down when pressing a note key) but I didn’t know how to do that so that the tape starts recording in reverse rather than forward when I trigger the sequence.
Turns out it’s hold down both the record key and the 5 key (with the reverse red R on it) and then trigger the sequence with a note key as normal.
I couldn’t find a way to “lock” the tape in reverse mode without keeping the 5 key down, so unless you’re Zaphod Beeblebrox you might have trouble recording complicated performances in reverse.
Also, be careful when you finish what you want to record, because as soon as you let go of the 5 key the tape starts going forward again but still recording. Unless you want that, of course. 
Thanks a lot! I didn’t know that. Shift and play! yay!