Here is the step by step guide to overclock your Honeycomb tablet straight from the developer:
Instructions:Here is the video of Motorola Xoom doing 1504 MHz!
1. Make sure you’ve unlocked your Xoom’s bootloaderfor flashing first, then root it.
2. Grab this zip and extract it. It includes a boot.img with the overclocked kernel and a corresponding wifi module: http://www.setcpu.com/files/xoom_ocboot.zip. Thanks to Koush for the rooted ramdisk in this boot.img!
3. Reboot into the bootloader by running:
adb reboot bootloader
4. Flash the boot image to your boot partition by running:
fastboot flash boot xoom_ocboot.img
5. Push the bcm4329.ko to your /system/lib/modules folder and reboot to re-enable wifi:
adb push bcm4329.ko /system/lib/modules/bcm4329.ko
You can head to the official XDA thread posted here for more info and to get hands on support if you get stuck with the tutorial.