That’s precisely what my VC-1 pull request is doing. You can set software decoding for 24p content and hardware decoding for the rest (ie interlaced).
There’s some glitch with the hardware VC-1 decoder and if interlaced isn’t set the movie doesn’t play at the expected frame rate. The bug affects even progressive VC-1 encoded files. That’s why all VC-1 content is being subjected to forced deinterlacing if you set the VC-1 hardware decoder to being enabled. And indeed you end up losing a lot of resolution for progressive VC-1 files. For actual interlaced content the hardware VC-1 decoder works fine, and the box isn’t actually powerful enough to deal with software decoding both VC-1 and deinterlacing.