A compressor would help a lot, although most of it is just tons of practice and strengthening your fingers.
There's also a trick you can use to mute other strings as you're tapping so it sounds clearer. Best bet is a decent overdrive, a compressor, decent pickups, light guage strings and the action on your guitar set as low as possible.
If you sign up for High Bandwidth there's about 60 lessons available with a bunch of videos showing all this stuff & everything from basic one finger tapping to 8 finger chord tapping

http://www.guitartricks.com/lesson.php?input=1873&s_id=13
http://www.guitartricks.com/lesson.php?input=1961&s_id=15
http://www.guitartricks.com/lesson.php?input=2059&s_id=16
http://www.guitartricks.com/lesson.php?input=2484&s_id=21