There isn't one patch in particular but the best ones include using compression to even out the sound, as well as some overdrive and maybe a little reverb or echo. Basically, just about any overdrive patch on the GT-8 will work. Just experiment with the compression.

There's a 50 page tutorial on tapping here:

http://www.guitartricks.com/lesson.php?input=1873
http://www.guitartricks.com/lesson.php?input=1961
http://www.guitartricks.com/lesson.php?input=2059
http://www.guitartricks.com/lesson.php?input=2484

..that should keep you busy for awhile.