If you look into the your main tcl startup file you'll find something like:
ns_section ns/server/$servername/tcl
ns_param library /web/$servername/tcl
The directory specified is where AOLServer sources tcl files. So in essence all the files in that directory are run at startup. (And any procedures defined are loaded)
Actually you almost got it right. What you should do is take the above script with the definition of the proc and the register_proc. Put it into a file (by any name with a tcl extension) in that directory. .../tcl/ should be fine. And give it a whirl.
