It is possible to run the alternate cabling. I used it with 7 speed DA shifter to an older XTR rear derailleur.

it with s probably worth a try. It is basically a 10% change in the RD actuation ratio by altering the cable attach point.

A 10% increase on 3.95mm cassette spacing does get you to 4.36mm for a 9 speed cassette. I would still run a 10 speed chain.

There have been reports that cable pull is not an absolute amount throughout the shifter range, however with a Centeron guide pulley it might be close enough.

John