Remember this instructions apply to N0N-wifi version of XOOM. And then please unlock your Motorola XOOM first -- do it before taking the root in action!
How to root Motorola XOOM:
1. Download this xoomroot.zip and unzip or extract the file inside your Android SDK tools folder.
2. Extract the contents into your Android SDK Tools folder.
3. Inside the SDK tools folder then open a command prompt.
*Make sure nothing is selected and hold SHIFT+Right click – select “Open command window here.”
4. Type: adb reboot bootloader
5. Type: fastboot flash boot rootboot.img
6. Type: fastboot reboot
7. Now hold your hand, to wait the reboot.
8. Type: adb remount
9. Type: adb push su /system/bin
10. Type: adb shell ln –s /system/bin/su /system/xbin/su
11. Type: adb shell chmod 4755 /system/bin/su
12. And now this next step you have a couple of options.
Option A: Push Superuser.apk in adb. Type: adb push Superuser.apk /system/app
Option B: Exit adb and download Superuser app from the market.
13. Congratulation you have managed to root your shiny Motorola XOOM.
Once you've finished the steps you can continue to install Android 4.0.3 or Ice Cream Sandwich to your Motorola XOOM.