Of course it's impossible. If we could, every game released today would be playable as backup on debug units as someone with access to 1.50 firmware would be able to extract and make dev package for everyone else.
Everything up to the "create a dev package" part - as you can not create a dev package that contains a retail encrypted EBOOT alas!
ok, so you are saying that upto firmware 1.60 you could install both retail signed packages and dev signed packages on a test, tool machine and then after firmware 1.60 they could only install dev signed packages.
shummyr, you hit the nail on the head. i took the week off fellas, so no crazy questions from me till Monday... lol. i'm pretty sure we'll see a leak of the debug 1.50 downgrade pup soon, everything else seems to be " falling of the back of a truck" lately.
research is the key, if you have access to the sdk docs, then almost everything you need to know is there.