So I was looking at the changelog for 2.6.20, and it appears the kernel guys completely ditched ftape because "it isn't used by many people" and "it's outdated." Nice, really nice. ftape is used by much more than old little 200mb tape units; the later Travans can be ftape-driven and such. anyway, it looks like my only choice is to drop to a much older kernel to use my old tape drive!
if anyone comes across a better idea, let me know.