I've only half been following this thread, so please forgive me if I've got completely the wrong end of the stick about what's going on here and what you're after....but, presumably the caddy pops out of the the dds drive very simply? ...and (from the looks of the pictures on thomman that Peter posted) it looks like the drive just pops in to the caddy pretty easily. True? then read on. If not, then don't bother reading further!
If that is the case, how about using a hard drive docking station? Something like this: http://cgi.ebay.co.uk/Winstars-Commu...-/130468028378 (I happen to know this particular ebay seller personally and got given one of these as a little pressie the other week, and it's just dawned on me that this might be useful for what you're after)