www.chinaphonearena.com

What's needed:
- [Only registered and activated users can see links Click here to register]. Has everything you need to root your THL W8. Includes superuser, MTK6589 drivers, CWM recovery and scatter.

- Your phone
- USB cable

Full tutorial on the main site - [Only registered and activated users can see links Click here to register]

Quick and dirty:

• Install [Only registered and activated users can see links Click here to register] and verify in device manager
• Copy superuser zip to your external SD
• Run [Only registered and activated users can see links Click here to register] and load appropriate scatter
• Turn Off Phone, pull out the battery for 5 seconds and put it back in
• Click 'Download' on Flash Tools
• Plug in Phone - You will see it install the recovery. It should finish with a green circle
• Boot into recovery by holding vol+ and power together
• Select 'update from SD'
• Navigate to the previously copied superuser zip and select it
• Reboot and verify root

Gizbeat won't be held responsible if your phone bricks or dies. You attempt at your own risk.

Well I tried to follow this faithfully but I had some problems and had to make a few changes to make it work for me.
The driver for when the phone is in usb debugging mode wouldn't install.
I installed pdanet+ and this resolved the driver issue and I was able to install CWM recovery.
Unfortunately, I couldn't get the phone to enter recovery mode with the vol+ power combination no matter what I tried. I installed the adb tool onto my laptop and successfully entered recovery mode by sending the "adb reboot recovery" command from the command prompt.
Ok now in recovery mode but a little nervous because the screen is a mess. Its showing the menu at the top and a ghost of the menu at the bottom and a load of fuzzy lines all down the right hand side. Well it might have looked awful, but it actually worked. I was able to install the superuser zip and reboot successfully.
All looked well but it wasn't rooted.
Fine, I'm not giving up that easy, so I download a new superuser zip from clockworkmod, installed that and now its rooted.