Silvertone,
If you really want to use the key of Db Minor, you might try using the keysig for Db Major and add in the extra flats (and double flats) as needed.
If you take a look at Liszt's
Consolation no 4, he begins in Db Major takes a brief turn to Bb Minor. Then in mm. 10-13, he really suggests Db Minor, adding in B-double-flat and Fb. Yes, this is only a brief suggestion of Db Minor with no usage of some crazy key signature.
I am in no way suggesting it is normal -- or even a good idea -- to use Db Minor as primary key for a piece. C# Minor is, of course, the logical choice. But, in some contexts Db Minor might make sense.
Mitch
PowerBook G4 (1.5) Mac OS X (10.4.8) LogicPro 7.2.3