Nevermind. It's facepalmingly simple, but really difficult to find. To spare any other poor sap who searches without success for such and easy thing like I did here is the answer.
To borrow a network license for AutoCAD Raster Design 2007 (2008, 2009):
1) Select the Image pull-down menu.
2) Select 'About Raster Design...'
3) Click the Product Information button at the upper right of the dialog box.
4) Click the Borrow License button.
Why they hide it there, one will never know. Sheesh.