Later supplements, including most of those sold through e23, have GURPS mechanics available for any new powers and for the sample characters.
There is also a conversion guide for the Liber Canticorum at
http://www.sjgames.com/innomine/arti.../ginsongs.html and a conversion guide for the Ethereal Player's Guide at
http://www.sjgames.com/innomine/arti...epg-gurps.html . These two are fan-created, but as Beth says on the LCant conversion, "The following is not canon -- but should the need for canon ever become pressing, the authors of GURPS In Nomine are not over-proud and would most definitely start here... "