Can CustomPress be used to Edit the Read More Link?

I need to allow bloggers in a new site to set the link the Read More text in excerpts points to. Can I use CustomPress to do this?

If not, does anyone have any ideas how I can accomplish this. I read an answer to a similar question on SitePoint that suggests custom fields can be used for this purpose. Unfortunately, I'm using a Genesis child theme and it doesn't use the_content() (as mentioned in the answer).