In short.
If you want to Reset Glitch it (being able to play backups from the HDD + playing homebrew etc) then you CANNOT acess XBLive.
If you want to flash your DVD drive (being able to play backups from DVD only) then you can acess XBLive.
A Slim 360 requires their drives to be unlocked.
So you'll have to do the Kamikaze hack or the Sputnik 360 on the drive.
At the moment only Liteon drives can be flashed from 360's Slim.
Partly true, not
all Liteon Drives can be flashed (yet). Liteon drives for the Phats (AKA Liteon Model Number DG-16D2S)
, came with a asortment of firmware versions 74850C, 83850Cv1,83850Cv2, 93450C, all of which can be easly flashed. Then M$ came out with a dashboard update (dash 13146) that took all those drives and reflashed them to firmware version 02510, of which is the latest Original FW for the phats, (and is still flashable).
Then M$ changed drives when they released the Slims . The Slim Liteon Drives come in different models (please take note I said models not firmware). The first model was the DG-16D4S this came in firmware versions 9504, 0225, 0401, and 1071. M$ again released a dashboard update to address the 9504 firmware (dash 13146) that took the 9504 firmware to version 0272. Them M$ released another dashboard update (dash 13599), this dash "locked" the drives, which requires one of the unlock methods that was described above. I might also add that buing a new PBC is also a methoid that is used to unlock.
The other liteon model for the slim, and I might add the newest; is the DG-16D5S, this has firmware version 1175, and at current time is not flashable.
A good website to start your journey is C4eva speaks.com, it will list all the drives and the most current CFW for your drive. Another website that is very good is team-xecuter.com, they have very strict fourm rules so read through everything prior to posting, but you can read through all the tuts without starting a membership. Also cruse over to jungleflasher.net and take a look as well.
Happy Flashing Sir!