how do i set k-meleon as default browser?

There is an option to do so during the installation program. I think the only other way to do it is to manually edit your file associations (*.htm, *.html) to point to k-melleon.

That won't make it the default browser though. You would also have to edit your associations for HTTP and HTTPS. This should be added to the GUI somewhere I think.

Open any folder, go to Folder Options under Tools. In file types, the protocols might be listed. If so, you can change them there or at least get a good idea of what to change in the registry.

The easiest no hassle way to do this is to download the program called "Set Browser" at http://www.pc-tools.net/win32/freeware/gui/

It's free and will make all necessary changes to your system to set K-Meleon, or any other browser for that matter, the default.

Another way:

save an html file to your PC, hold shift > right click it > open with.. > kmeleon > check always use this program to...