external mics are best for recordings, internal are wicked for live gigs, unless ur doing somethin traditional and ur not moving around too much. if u want to do it properly and neatly find a decent size bolt that fits and screws into ur mic clip. position it in the center of the barrel where u plan on drilling ur hole. make sure u use some washers on the inside as well. they give it a little space so the wood doesnt crack. position ur mic as you wish, personally i've tried many different ways and have seen alot of mics in dif dhols, best way for most dhols is slightly slanted pointed towards the dagga..not directly facing it. you wanna pick up both low and high end frequency. map out another place for another hole where u wanna put ur xlr connection. u can use a straight up xlr cable with a bracket or get a xlr connector. it takes some time.
hope that helped a little bit.