1) Get the updated CLM installation files (See issue 5 in KB946797)- The specific CLM FP1 build number which includes W2k8 support for CLM 2007 is 3.3.1087.2 which is currently (03/03/2009) only available through Microsoft Support.
2) Configure IIS on the CLM web server to have Windows Authentication enabled (in Roles in Server Manager).- IIS 7 has only Anonymous Authentication enabled by default.
3) Extend the W2k8 AD Schema with the CLM attributes- You need to run the schema upgrade from the DC with the Schema Master role and be logged on with a member of the Schema Admins group.
Once these steps are in place, you should be able to follow the same installation procedures as for Windows Server 2003.
Note: Any certificate templates on a Windows 2008 CA you want CLM 2007 to be able to use *must* be created with the Windows Server 2003 backwards-compatibility option selected.