Ok, I used the git clone command to get the sources, and then went into the mudlet directory, and issued: su ./build.sh
It built, but would not install. It failed while looking for the file: mudlet/src/mudlet/mudlet
Basically, it couldn't find the mudlet binary that it had built because the file is actually in mudlet/src/build/mudlet.
I took a look at the mudlet/src/build/cmake_install.cmake file, which is dynamically generated. It's line 44 that has been generated this way.
When I go in and manually change the target in line 44 of the mudlet/src/build/cmake_install.cmake file and then run sudo cmake -P cmake_install.cmake it installs just fine. And runs ok.
I may tinker with some of the source files a bit to see where that install file is generated from, and post back if I find it.