I found them in a local sports store in Melbourne, so probably wont help you there? The mallet method would do the same thing.
This is directly from Go Jeeps site:
http://www.go.jeep-xj.info/HowtoBumpstops.htm
As soon as you are over 30" tall tyres ( even earlier if not a sport ) then you will need to lower your bumpstops to prevent fouling the guards under full compression unless you do major trimming. I run 31.2" tall tyres ( 275x70x16 ) and have 2" lower bumpstops than the sport stock which are about 1 1/2" longer than stock already. The mistake is often made that if you raise the suspension than this is not necessary but that is false because even at 12" of lift at full compression the tyre still ends up in the same spot as a stock XJ.