I got the latest beta WLM running without any hiccups.
The easiest way is to run WLM installer on a regular windows machine and copy the messenger.msi and contacts.msi to your server 2008 machine and install both of them.
Of course, you need to search for the two msi files. They should be inside some temp folder…. forgot the path.
Start > Run > type in %TEMP% and hit