Can you please try the following from a command line:
msiexec /i wcfuniten.msi /l*xv log.txt
and send me the log.txt file. What version of the windows installer is on the machine in question? It is possible that it might need updating, I have never tested the installer on Server 2003.
If you need it urgently you could always install it on another machine and then copy the binaries. If you need Visual Studio integration then you need to look at the sources and find the command file deploy.cmd in the VSIntegration project, that shows you
how to install it into Visual Studio. You could get the zip file mentioned from the installation on the other machine, or just zip these files from the VSIntegration project (no need to build the solution):