Upgrade to slimserver 6.5.3 see change log for details.

http://www.slimdevices.com/Changelog6.html

Add largely untested support for changing the slimserver user, group,
and database/cache directory with the SLIMUSER, SLIMGROUP, and SLIMDBDIR
make variables. Make sure the user/group exists before install if you
use a non-standard one.