I'd like to model some compounds with DFTB, but some elements don't have parameter files in the official site. Is there a workaround?
I recommend you try out xtb by the Grimme group. It is a state-of-the-art Tight Binding program parameterized for elements up to Radon (already built-in). There is a small caveat: the only precompiled binary they distribute is for Linux (but the program is open source, so you can compile it yourself if you want.)

And yes, it is really fast.