Nope, you're limited to 26 drives because the OS will only allow you to use each letter once.
If you need more and you can NOT use UNC paths (e.g. \\ServerName\Share\Directory\File.txt) for some silly reason, your only option is to release drives your not currently using and then map them to someplace else.
You could write a batch file which maps a bunch of specifi drives that an application needs, have it launch the app, and then release the drive mappings when the app exits.
Dave