These folks have sight pushers for rent:
http://www.speedshooterspecialties.com/index.php?main_page=index&cPath=80&zenid=a88dcd2a202896d3106346075d1dc540
I installed one in my 642 using their YouTube video's as a guide, and I feel it was well worth the $25.
I have a 342 coming and I plan to buy another kit soon!
I've been very pleased with all of my Apex Tactical purchases.