Custom checkin policies and custom work item controls are great ways to take advantage of the extensibility of TFS. You can use checkin policies to enforce certain standards on checkins (even in your builds). Custom work item controls allow you to add controls to your work item forms that present data in particular way, access other systems, etc. However, there’s no mechanism in Team Explorer to download and install these.
Youhana has written a post on how to use a feature in the power tools that not many folks know about. By creating a couple of version control folders in each team project, you can have folks use the Team Members node in Team Explorer to download and install them. This means that your users don’t need to know where to put the files on disk or the registry entries to create to make them work. There’s not an auto-update mechanism there right now, so users will need to do this again if you subsequently update the dlls. To get to this feature, you need to have the Team Foundation Server Power Tools installed on each machine where you want to use this feature.
The team members component of the TFS power tools (available here) has a feature to help TFS users distribute custom check-in policies and WIT controls. Basically, the administrator would add the dlls containing the policies and components to a special folder in version control and users then can install the components using the “personal settings” dialog in team members. These are the detailed steps: