Any gunsmith worth his salt that does precision rifle builds will be able to install an AICS compatible bottom metal. If the stock isn't already inlet for the bottom metal then it could be challenging to do it yourself since the depth and alignment of the pillars is critical for it to function properly.
There are a lot of options out there now and I've used a handful of them from Badger, Greyboe, Stockys Stocks, and Magpul and they all did the job pretty well. The basic Stocky's Stocks M5 is a pretty good value at $140 and the Greyboe M5 DBM isn't bad either for a little more money, it's a quality piece for sure.