Dispensations can be issued only on a temporary situation and if other limitations are observed or implied. A dispensation may be valid only for a ferry flight, positioning etc...
As a matter of fact, the procedure is very similar to obtaining a CofA for ferry to maintenance.
There are, however, airlines around, which provide their own "dispensation" on a permanent basis. I.e. removing MEL pages from the manual....very difficult to spot as the MMEL is usually not available to cross-check.