elvis top 20 fruit machine boot up problem?

I have the above category B3 machine which boots in windows xp and then onto the machines program. It was accidentally rebooted in cat D mode and therefore wont reach the b3 program. How can I interrupt the windows boot process and get into the elvis program? Can I adjust the files and get it to re-boot in cat b3? Is it an autexec type file? Any help MUCH appreciated!!!