[openbox] Changing Cursor Size/Theme Without Restarting X

[sunnycemetery at gmail.com]

Is it possible to change cursor size on the fly?  Documentation I found  
says to edit the ".theme" file and restart X.  I would like to be able  
to immediately switch to a large, high-contrast cursor when sitting in  
a distant chair but back to a small, black cursor when close to the screen.