To get better help, try to be more specific.
Do you need to control all their work apps and environment and keep the data local? If so, you could employ a Terminal server (best over VPN).
Do you want to give them remote folder access to specific files? If so, you could use a VPN solution (or use PPTP or whatever your Win Server version has). You could even use FTP, HTTPS or a free service like Dropbox). http://www.dropbox.com/tour
How many agents do you have? How many are likely to be signed-on simultaneously?
If you don't have the project funds for a terminal server, you could group a few similarly configured "old-schlager" PC's together and change their RDP ports for the occasion... This is called security by obscurity...(try to use random high port numbers)
(Don't forget: Setup each with good passwords and matching port forwards on the firewall). see: http://support.microsoft.com/kb/306759
Lots of fun! - CM