I use generic setup to setup the memberdata properties. Two Files are available, but i'm not sure if it necessary that both are manipulate. memberdata.xml and memberdata_properties.xml. you can export these files via portal_setup.
portal_memberdata = getToolByName(site, "portal_memberdata")
if not portal_memberdata.hasProperty("home_folder_uid"):
portal_memberdata.manage_addProperty(id="home_folder_uid", value="", type="string")