hi guys, sorry for the confusion of previous description.
Now forget the "Macro" and "Auto Clicker",currently in live server, u have to use this addon http://code.google.com/p/wow-bg-twinker/ and the video guide http://youtu.be/lViRnUWdKrw

Addon Guide
1. simply download the zip file,extract and copy "BGTwinker" folder into "World of Warcraft/Interface/AddOns" (also there r many guides on youtube teach u how to install an addon)

2. check "Loading Out of Date Addons" (on toon selecting screen, theres a button on the bottom left corner)

3.queue for a bg when your xp are NOT freezing, then find the "Experience Eliminator" and have the XP lock window popup, and stand there dont move.

4.when the bg window pops up, simply click "accept bg" will do the trick

Additional Guide
When the exploit fail,follow instructions below:
=Getting a deserter debuff=
server side issue,I can't fix it.
=In BG but XP not freezed=
Change the addon setting by typing "/bgt number"(default number is 0.4) , For instance type "/bgt 0.25". Reduce the number until you can get in BG.
=XP freezed but not in BG=
increase "/bgt number"
(btw i set my bgt number to 0.2 and it works 95% of the time)

~~~~~
This exploit helps you to get in XP-on bg and slaughter lowbies.
You can gear up with full 79 Cata gear for your twink and stay in 79 bracket forever.
The 79 bracket is the easiest,because you can buy all Cata gears in AH,and with these gear you can do triple damage than usual ppl.