Cool. Bummer it doesn't work on 528. Then again, Openbox has an on/off switch. Must be the updated JWM..
Might it be that it looks like you're supposed to edit /etc/xdg/templates/__root__.jwmrc as that's the template that gets copied into /root/.jwmrc ???
I had a similar thing with /root/.gtkrc-2.0 which was over-wrote each time the gtk theme was changed. Made the changes instead in a include file /root/.gtkrc_mine (I wanted slightly slower mouse double click detection speed (half a second between clicks) as I've set ROX-filer to use double click based control i.e. added
gtk-double-click-time = 500
to a newly created .gtkrc_mine)