Having admired Andy's work the guys at AMC stumbled over the motherboard -> 9-pin D lead - here are the pins for doing it on an Intel 7501 motherboard (see page 155 of the manual).

IDC to 9-pin (male)
1 - 1 -> DCD (red-stripe on ribbon)
2 - 6 -> DSR
3 - 2 -> Rx
4 - 7 -> RTS
5 - 3 -> Tx
6 - 8 -> CTS
7 - 4 -> DTR
8 - 9 -> RI
9 - 5 -> GND