Ok. Once you SBF and have the clean "stock" system (it doesnt matter which one, technically, I'm on .890 I think
):
1. Achieve Root
(Stealing this from guidot's guides over in the hack thread)
1. Make sure "allow 3rd party apps" is checked so you can sideload SafeStrap
2. Find the apk in your download folder.
3. Install the SafeStrap app.
4. Open the app from your app drawer.
5. Allow root access.
6. Select 'Install Recovery.' This should take a moment; when it completes, 'Recovery State' should show 'Installed.'
Now, you are ready to reboot into recovery.
1. Power the phone off and power it on.
2. You will come to a splash screen that states, 'press menu for recovery access.' You have 10 seconds, otherwise the phone boots normally.
3. Once you press the menu softkey, it will boot into ClockworkMod Recovery
To flash a ROM:
1. Make sure the ROM .zip file is on your SDcard
2. Reboot and access recovery as above.
3. Select Safe System
4. Turn on Safe System (this should take a few minutes as it is copying the userdata to an unused partition)
5. Power off and reboot into recovery
6. Select mounts and storage
7. Format /system
8. Back to main menu
9. Install zip (MavROM) from SDcard
10. wipe data (in main menu)
11. wipe cache (in main menu)
12. Reboot (should take a good while to boot, up to 5 minutes)