Hopefully it should work fine for you.
If you have problems editing the file (vi is not for everyone) let me know and I'll see if I can put together a script to do the modification.
As a followup to this idea, if you use UPnP occasionally, you could still make this change to the inittab file, and then have two scripts available on a share that you can see.
One script for enabling UPnP
and the other script for stopping UPnP (and cleaning up the desktop)
but this stop script would only work properly if you've made the change to inittab.