I dont use Google Adsense, so I do not know for sure. However, you may want to look at the module called Banner Manager. I've never looked at it, but I imagine it is designed to place an advertisers code in your templates without editing your templates.
On the other hand, you can just ad the Google Adsense code manually in your templates wherever you want it to display.
Robert Angle
Phorum lover, nothing more.
Ruminations