You will be asked for a BIOS file (lynxboot.img) at first start-up, which will be copied to appdata. You will be warned if the BIOS checksum doesn't match that which the PND expects.
Controls:
D-pad: D-pad (duh)
Pause: Start
A: X
B: A
Option 1: Y
Option 2: B
Default is to run with an "LCD" effect which looks like scan lines. If you want to turn this off, make a file named "nolcd" in appdata/handy but be warned that you may need to crank up the MHz as the software rendering is pretty slow.