It is not possible at this time... and probably never will be; and the add all only adds the all current packages from that category, too. IE: if new thing is added, you'd still need to come back and add them again...
This is due to resource constraints. We currently have approximately 3093 users (according to top counter), and for every time we update source (approximately 1 hour per source, we have approx 50 sources in system), we have to add new package to all 3093 users, and then more as we get more users. This becomes a massive overhead on the system, and in reality, unless the source is small and useful (IE: Saurik's Cydia + Java source), there's no real need to add everything... (and to continue the example, Saurik already have them classified into specific categories that are useful and easy enough to add all with what we have).
It's quite unfortunate, but I'd need to figure out a way to effectively manage the tracking packages in order to achieve that... for now, I don't even have time to add sources to tracking (*cry*) with much blame to my course project; let alone promised features --
Package Details view -- and ease of use improvements :/
I'll be done with schools officially, for good, in a few weeks' time (approx 2 weeks time)... so I'll have a bit more time to work on things then (expect lots of new stuff being pushed out in the month to come after that). Hopefully, I'll have a chance to sit down and do that after I code everything I've got on the drawing board already.