Can you convert an older '04-05ish record 9 speed short cage derailleur to a 10 speed?

No conversion available or perhaps necessary. Try it out as-is. It might work as others have reported; or if the travel is different in the RD you'll have to get a new one.

Since 2001 the geometry/travel of Campy 9 and 10 speed derailleurs are all the same. The only thing you need to change is the pulleys, which are narrower to accomodate the narrower 10-speed chain. Of course, you need 10-speed levers (or convert your 9-speed ones by installing a new indexing cog).

Since 2001 the geometry/travel of Campy 9 and 10 speed derailleurs are all the same. The only thing you need to change is the pulleys, which are narrower to accomodate the narrower 10-speed chain. Of course, you need 10-speed levers (or convert your 9-speed ones by installing a new indexing cog).

Ditto all the above. Just a minor comment: 9spd was introduced until '97, so a '94-'95 derailleur would technically be an 8spd derailleur. However the only difference between Campagnolo 8spd and 9spd derailleurs is a minor change in pulley width - I've been using "8spd" Campagnolo derailleurs on 9spd systems for years.