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Sounds like any easy enough install if you've got all of the tools and bits to do the work with. I'd highly recommend Hunter's Sporting Goods - Sparrow here can probably help you out....
Hunter's, Dlask. Or buy the tools and do it yourself, pretty simple (will take about an hour and a half to two hours your first time) Check http://www.ar15.com/forums/topic.html?b=3&f=4&t=226782 for info on installing the forearm, they have complete step by step instructions with photos and tons of advice. Just scroll down to the forearms install part, they even do a Larue.