You'll need to do some custom edits to your template as the 3-bars are set in the template, not the SCLogin module.
To start, you can do something like:
a.btn.btn-navbar.collapsed {
background-image: url(http://rainbowrv.com/images/Logowithwords.png);
width: 100px;
}Test that out (with the right image) and see if it helps.
Thanks,
Alex