Great! Strangely, when I tried this before it did not work, but now seems to. I may have been missing a dependency before and just assumed that "deprecated" was really now fully gone.

Update: I searched my history to find where I tried it previously. It turns out there was a unicode point 151 (which shows nothing in the terminal) immediately following --scandeps, which caused cpanm to tell me 'Unknown option: scandeps'