If you're talking about the ones that load in the theme in the footer, that probably means a lot of work. The way the theme works, the php calls up some CSS, which then loads up a social_icons.png file, but each commands loads a certain part of the single image, rather than loading a bunch of smaller ones (which is good). In other words, you'd have to do a lot to get it your way.

Easier way? Get the Social Media Widget plugin. It's very simple to use, and as a widget it looks nice and you can load custom icons like Google +. If you look on my site (dentondemocrats.org) you'll see on the right we have the larger icons, plus one that goes to ActBlue, which I made fairly easily. I did the same for Google + on my personal site with the same plugin.

Is there any way to add Google +1 to the Social Icons?