First things first! Do your prep work.
In my case I am rooting a Wincen Telechips 8902 that has WinCE partition and an Android 2.3 partition. The WinCE side handles the dvd/cd, ipod, rds, ATSC tuner, AM/FM tuner and aux AV inputs. The Android side handles the gps receiver, wifi, and 3g. It shares av inputs, nand and ram with the wince side, and I have to identify the right usb to establish an adb bridge.
There are 3 usb connections, with two in back to the android side and one in front to the wince side. It also has teo sd card slots, one for wince side, and one for android side. In normal operation, the wince side is for firmware updates and music, and the android side is for maps.
Taking a hint from the pocketables guide, I am rooting my unit using so I can dump the android rom first.
Once I have it rooted I am using romdump to make a dump of the android side.
After creating a recovery of the android side using romdumps output, I will then use wince tricks to dump the wince side and make a recovery of it as well.