Can I have three Remote Desktop sessions to a 2008 server without installing Remote Desktop Services?
Solution 1:
You can't in 2008 and later. If you want three concurrent users, you'll have to install the Remote Desktop Services role and have the appropriate licenses.
Using that trick in 2003 was actually a violation of the license. Without buying the appropriate CALs, you were limited to two concurrent connections for server management only both then and now.