Customize successful login message?

Hi, when I use this plugin to create a front-end login form, on successful login I get this:

“You are already logged in. (link to “My Account” page)Log out?(end link)”

I would like to be able to customize this message and link to:

a) change the “You are already logged in” text because it doesn’t really make sense to see that message when logging in for the first time, and,

b) use a log out link that doesn’t redirect automatically to the “My Account” page but to a page I can specify.

Is this possible?

Thanks