Yamaha DTXpress/DTXplorer/DTXtreme

I use a Gibraltar double basedrum kick drum pad ... simply cut down a
few inches on either side , only 3 or 4 bucks at your local music
store. it already comes sticky on one side , but if you add a little
spray adhiesive to the back of the gibralter pad for extra stickyness,
it bonds very well...... i too used the mousepad at first , but found
it came up around the edges and would hinder the beat i was playing,
hope it dont start coming loose during a show!... but  the Gibralter
pad worked  a bit better as it is about a 1/4 of the size of the mouse
pad, and looks cooler too :) with a nice logo.
. hope this helps.