Skooter, alive15, dahonora, jpsantos96 - as far as I know, in R-30iB and later there's no possibility to make z backup using MC. I suppose they stopped supporting it. It was working until R-30iA.
But when I have a chance to have R-30iB in my hands I'll make a try myself and let you know.
I must admit that you made me go look to verify the R-30iB Main Board had the PCMCIA port. Like pdl says, it seem more reliable and it works when the USB ports might not be the best option due to foreign material in them.