If I remember right you need to go in and modify the controls. In order to do that you have to us the default keyboard controls to navigate in and customize them.
OK, I got my manual out. The default controls are on page 4 of the little jewel case manual. Using those controls go into arcade, then options, then system options, then controllers. Page 10 in the manual tells how to actually change them.
Warning - I could not get the game to let me map any controls to the CTRL key. Like I said above, I ended up re-mapping my IPAC around keys I was able to get Blitz to use, keeping it as close to the MAME default as possible.