Button configuration:

All buttons on the Dreamcast controller are in the same location as those used for SNES emulation, with the following exceptions:

Start - you must press Start+A on the Dreamcast controller to emulate the "Start" button on the SNES.

Select - you must press Start+X on the Dreamcast controller to emulate the "Select" button on the SNES.

A on the Dreamcast = B on the SNES
B on the Dreamcast = A on the SNES
X on the Dreamcast = Y on the SNES
Y on the Dreamcast = X on the SNES
Left trigger on the Dreamcast = L on the SNES
Right trigger on the Dreamcast = R on the SNES

Both the D-pad and the analog stick may be used for control.

An in-game menu can be accessed by pressing Start+L+R all at the same time.
Of the many features listed, only two are currently available, "Reset SNES" and "Select Game"
Selecting another options will simply return you to play where you left off.