Process Designer - creating new PD module from scratch - dead end ?

According the marketing stuff and official product documentation (e.g. "Proces Designer Tailoring Best Practices Guide") it is possible to create new PD enabled module in SM (i.e. new table, new security module etc.  to support IT related but non-ITIL processes  e.g. new hire). However the procedure described there leads to nowhere - the newly created module doesn't work.... only works in db Administrative mode, not using PD mechanisms). Where is problem ? Or it is only marketing "falsehood" and PD is hard-coded for standard modules only and nothing more ?