I got a question from a customer who is trying to use the instructions in this blog post to perform a silent installation of VS 2005 and MSDN. They ran into a problem where MSDN installation failed, and tracked it down to an issue where the C drive on the machine did not have enough available disk space to install all of the help content. Setup was silently failing because it was being run in silent mode, and the customer had to rerun MSDN setup with verbose logging (using the steps here) to figure out why it rolled back. Once the customer figured this out, they noticed that if MSDN setup is run with full UI, they could change the path in the UI and install successfully. So the next question logical question was how to modify the silent install command line parameters to allow MSDN to install to a non-default path. After digging through the verbose log file, the MSDN MSI, and finally talking to a developer I know on the MSDN setup team, here is a command line that can be used to install MSDN setup silently to a non-default path:
setup.exe MSDN_QTR.3643236F_FC70_11D3_A536_0090278A1BB8="MyPath" /qn
In this command line, MyPath can point to any non-default location - for example d:\Program Files\MSDN\. The path does need to be quoted in this command line. Also note that if you want to, you can change /qn to /qb to cause a small progress dialog to appear during MSDN setup.