I was having a problem with the mlxcc and ruby loading it. Here's how I got around it.
I downloaded the mlxcc source directly (I needed 64 bit for my Ubuntu server) from subversion at xqzone.marklogic.com.
There is probably a way to use the subversion source, but I was able to download the mlxcc-0.5.3.tar.gz instead and use the standard install I am more familiar with. The subversion source appears to be using autoconf and I wasn't familiar with what needed to be done to install.
I ran ./configure and
sudo make install.
Next, the Ruby Gem
From the subversion source I ran
rake gemand then
sudo rake install.
The one thing I had to run was ldconfig because the library file couldn't be found.
rake alltestsshould show that your ruby mlxcc library is now working.