Hi Matt,
I converted my own battery grip, originally for my 1000d and recently for my 7d. Here is my original thread. I have been using this system for 3 years with no problems.
http://www.iceinspace.com.au/forum/s...ighlight=canon
A quick search on ebay found that this would be a suitable grip for conversion.
http://www.ebay.com.au/itm/BATTERY-G...item2eb89f13f7
I used the electronics available from Jaycar found here.
http://www.jaycar.com.au/productView.asp?ID=KA1797
I hope this helps, I also know that there is other units available that are pre made that have been recommended by other users here.
Trent