[kde-linux] kde default settings directory

[Nathan]

I know in KDE 4 I can use 

  -DKDE_DEFAULT_HOME='.kde4'

to change the settings directory, but how do I do that with KDE 3.5.10 ?
I would like my kde 3 settings to go into .kde3 and my kde 4 settings to go 
into .kde4 or .kde

Are there any problems with leaving it all going to .kde for both kde3 and 
kde4?

Nathan