I don't think is possible on KDE 3.5.10, I haven't use KDE 3.x like in 3 years, there may be some workarounds, but I highly doubt it, since kdesktop just reflects your "~/Desktop" content, maybe by modifying the source code itself, and make a little kdesktop2 fork (you may only need to change the path it reflects), then again, I have never seen KDesktop code in my life, but it may be possible.
However, it's certainly possible on KDE 4.2 :-P
This post has been edited 1 times, last edit by "augustofretes" (Jan 21st 2009, 4:01am)