suPHP support is enabled on compilation only. You will need to have suPHP compiled, configured and have correct header on you system before compiling it.
To enable suPHP, you have to enable the compilation variable HAVE_MOD_SUPHP_SUPPORT in the Makefile or in the apxs command line.
Check that mod_suphp is compiled with SUPHP_USE_USERGROUP to get full support (if there is a good way to get sure of that while loading mod_vhs as module, contact me).
A new configuration variable is added to the apache virtual host configuration:
vhs_suphp_config_path /users/%s/config
The %s will be replaced by the username which libhome gives back for the hostname. SuPHP will look for a php.ini in this path for the given user, it basically needs to contain only one line (or whatever options you want to change for the user):
open_basedir = /users/MYUSER/data
mod_vhs will set the SuPHP-Variables suPHP_Engine, suPHP_ConfigPath and suPHP_UserGroup for each request in the vhs_suphp_handler-method.
The first problem here is that suphp expects a per-directory configuration, which can only be set in the handler, but not in vhs_translate_name method.
This is for now basic support, if you get some more patches and updates don't hesitate to contact me.
suPHP support is not compatible with MOD_PHP support in mod_vhs. You will have to choose between standard mod_php support and suPHP.