It is not a KDE problem, but a X-Window problem.
If you have XFree 4, no problem, there is a server for TrueType fonts included.
In XFree 3, there was not yet such a server, but an extrnal program existed to use TT fonts. (Sorry, I cannot remember the details, especially as I have never used it on XFRee 3.)
Have a nice day!