It is now possible to use the Team Foundation Service Preview (Microsoft hosted TFS) with Visual Studio 2008 and BIDS (VS 2008 Shell).
1) Install Visual Studio Team System 2008 Team Explorer http://www.microsoft.com/en-us/download/details.aspx?id=16338.
2) Install Visual Studio 2008 SP1 even if it is has previously been installed http://www.microsoft.com/en-us/download/details.aspx?id=10986.
3) Install the Visual Studio 2008 SP1 Compatibility GDR for Visual Studio 2012 Team Foundation Server and Team Foundation Service Preview http://www.microsoft.com/en-us/download/details.aspx?id=29983.
4) Add your server (assuming you've already signed up for TFS preview) using the following URL: https://<yoursite>.visualstudio.com/defaultcollection.
If you receive an error stating:
TF31002 Unable to connect to this Team Foundation Server...
Possible reasons for this failure include:
-The Team Foundation Server name, port number, or protocol is incorrect.
-The Team Foundation Server is offline.
-Password is expired or incorrect.
MAKE SURE YOU ADD /defaultcollection to the end of your URL.