XTrkCad is a project at SourceForge
You can download the latest source on Linux by
cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/xtrkcad co xtrkcad cd xtrkcad make cd lib export XTRKCADLIB=`pwd` cd ../bin ./xtrkcad
See the README file in the toplevel directory for the current state.
MS-Windows build instructions are pending