"The 757/767 can't track a raw VOR radial. Only a LOC or a RNAV track"
I beg to differ. Though I'm sure it's only semantics.
The 757/767 can receive VOR's just fine. It's called "raw data" and it's what you get if you go to manual tuning on the MCP and enter a VOR freq and course. I think that automatically takes you out of map mode on your EHSI, as well, or maybe you have to select it, I can't remember. Anyway, you could "track" a VOR course using heading select just fine. But that's different from putting in a radial in the FMC. You can build a VOR radial in the FMC and use LNAV, too, but that's not "raw data" VOR signals. Of course, the FMC only understands a "course to", so in that respect, you kind of have to trick it into tracking a radial outbound by converting that into a "course to" fix. Which is what I think you mean by RNAV course.