mhash functions for my windows apache development server

I'm trying to set up a web page for credit card transactions and baffled trying to find a download for mhash functions for my windows apache development server. The real server supports mhash but I can't test it on my localhost system. php.net points me to http://pecl.php.net/packages.php where I don't see it in plain english, googling around it looks like this may be it: http://sourceforge.net/forum/forum.php?forum_id=585348 but it's short on giving me a clue.

help! I'm lost...
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