Best way to customize messages?

The admin interface is just what I need for my moderators, this is a great module.

However, on the user application page, the language is confusing in the context where it appears... and I wanted to change some text, for example:
"Apply for role" > "Apply to Participate"
"Select the role you want to apply for " > "Tick box if you are interested in participating in research... etc"

... so... I edited the source of the Module directly ... eek... *ducks defensively* I'm sure that is not the best way to do this.

I would like to have these messages editable in the admin area, but I haven't the foggiest how to go about making a contribution to this module. If someone can point me in the right direction, I can try to make this happen. Thanks!