yes you can (not sure with the BU manager tho) but if your ps3 is BC, then you can... i play all my PS2 hombrew stuff all the time... loading Ulaunch works, & running games works... some of the Ps2 media server apps cause the ps3 to reboot, or freeze tho...
What i would like to know & hopefully somone can assist, (as i have been asking about it for over 2 years now)
There are Ps2 games (a final Fantasy game, & a resdient evil game i belive) that utilize the HD option of the ps2. APPARENTLY when you enter those games into the PS3 & play, the game gives you a option to format a section of the internal HD to store stuff (so this means that a PS2 filesystem is created on the PS3 drive)
So tecnically, that partition should be assessablie via Ulaunch (maybe the PS3FTP also), i dont have either game, nor can i find them , so i cant test it out. But if my theroy is correct, then technically we could store all ps2 rips on the ps3 drive, & load Via swapmagic... & who knows what else