Here is an Android 4.2.2 Jelly Bean rooted firmware for the PIPO M8 PRO tablet (3G model) based on latest official update from Pipo dated 2013/06/28

(update_PIPO_M8 pro-3G_EN_2013628.img)

Build information: 

Kernel: Linux version 3.0.36+ (root@alex-System-Product-Name) (gcc version 4.4.3 (GCC) ) #117 SMP PREEMPT Fri Jun 28 15:56:00 CST 2013

Android 4.2.2 JB: rk30sdk/rk30sdk/rk30sdk:4.2.2/JDQ39/eng.root.20130625.205128:eng/opinions-on-teclast-p90hdst-keys

Custom firmware features:

• root with latest SuperSU version 1.41 (free version)
• removed most Chinese and unnecessary applications, removed Certificate Center asking for product key
• Google Play Store fixes so more application are visible/compatible
• updated busybox v1.21.0.git (2012-11-29)
• Unix like init.d boot scripts support, more details on init.d scripts here
• changed permissions on external sdcard to allow write access
• increased space for applications (/data partition) to 4 GB

Download: kasty-pipo-m8_pro-422-20130628-rooted4.zip

Flash with Rockchip Batch Tool version 1.7, use Restore button.

Please report any problem with this firmware, I can't verify this custom firmware works as I don't have a PIPO M8 PRO tablet to test the custom firmware.