You should be able to find a tuner, either through PCA or through a resale.

I'm surprised to discover that the official PCATS site is down. Wonder what's up with that? Patrick's other site is here but I get the feeling he hasn't updated it in a while.

If you can't find a tuner, can you fit two stereos in the dash? You could have a CD player feeding into the empeg's Aux-in and still be driving the amp directly.