There is now a commercially supported Activation Filter available for download for users who do not want to develop/compile their own activation filter for HPC Server 2008:
Features for this release include:
No coding is required. A simple GUI for configuring FLEXlm licensed applications. Server configuration testing. Offline job testing. Extensive logging. Multi-Application support. Detailed documentation. Simple GUI installer.
There is a two week free trial for you to try it out. The step by step documentation is also on the same web page as the download.