Do you mean getting harmonics by tap on the frets? That's cool, I use to it on my bass (!). Works good aswell on my with Epiphone Speciell-II - Marshall MG30 and my Zoom505 aswell.

My settings are all "fifteen over". I think it's more about technique than settings.. I saw a great tutorial for this on the net somewhere.. Let me check.. I got it:

www.chopsfromhell.com

click on the CHF Online Columns and go forward to Wiretap.

I hope this helped you, dude!

Take care..