Confidential Mission question (no foreign light gun?)

This past week I picked up a used copy of Confidential Mission locally
for the Dreamcast. This is one of a few DC games I never got around to
picking up that I wanted to play. So I dig out my DC and hook it up, but
when I plug in my trusty Japanese light gun I get the message:

"No foreign light guns allowed!"

WTF? I know this is a old game and all, but is there any sort of work
around for this? It's pretty shitty they locked out the import guns as Sega
didn't release a first party light gun in the US. It works with all my
other light gun games, but not this one. Suggestions anyone? Maybe I
should just buy a used light gun off eBay....

Aaron