I hate to give probably useless infomation, but here goes anyway...
Iv'e often heard that removing the diff centre, from a R200 mind you, required quite a lot of coaxing with a pry bar.
I'd imagine it wouldnt be any different for you.
For what its worth here is a link I bookmarked for the day I eventually got around to it.
http://www.pexcom.com.au/z32cms/e107_images/How_To_Install_an_Aftermarket_LSD.pdf
I did have one by a guy doing a writeup on shimming a diff that had more detail and pictures of the actual centre removal, I cannot find it though.
Good luck to you
