Off-topic : Did you just put iPhone and awesome in the same line? LOL
On-topic : You don't need jailbreak dongle, iphone or whatever anymore. Just get a CFW. You can jailbreak as soon as you don't update over firmware 3.55.
Anyway, the only method of running PS2 homebrew on PS3 is soldering a switch on the BD drive and using swap magic and ulaunchelf.
As for backups, the best method by far is by using Cobra USB. It is a dongle, but it works on 3.55 (via CFW) and with it, you can load PS1 and PS2 isos via their backup manager.
In fact, maybe you can even load an iso of swap magic via their manager and run ulaunchelf with smboot (?).
EDIT : Just realized I'm contradicting myself, first I say you don't need dongle for jailbreak then I say you need Cobra USB. This is because Cobra offers extra features (such as PS1 and PS2 iso loading) that nothing else does. However they want to make money off it (and who can blame them?), so they force you to use a dongle.
PS3 Slim CECH-3004A 160GB
PS2 Slim SCPH-70004 - FMCB 1.8b