The campy shifters are the same, whether downtube or bar end. Just the handlebar plug is different.

I read Paul's copy, but cannot understand, if you are using the earlier shifters, why they wouldn't fit on the thumbie just as both shimano and campy fit on the down-tube shifter boss on the bike. You should scare up one and see if it will work.

<edit> oh, the late night dyslexia...You already have shimano dt shifters. Try to fit 'em!