Indeed there are several places where there are sentences that are contradictory or confusing so I went to the 32U4 datasheet, and the Micro schematic. I probably should have dug deeper before posting a question but in case somebody else has this question here is what I found:
Software Serial uses interrupt on change which on the 32U4 is available on all 8 of the Port B pins. The attached PDF shows the pin mapping.
PINS.pdf (28.8 KB)