How to update samsung galaxy tab p1000 i.e. 2.2 to 2.3. using ADB?
These are the steps to install/update a custom ROM from stock:


Install a custom recovery (Clockworkmod for example).
Copy the ROM zip to the phone sdcard (you can do this via adb).
Reboot in recovery (it will load the custom recovery).
Use the option to install zip from sdcard to install/update the ROM.