Yes I have done it, works fine, transport and arm the X48 tracks record from the DM4800.
The RS422 wiring is (db9 male on each side) : 2 on 2, 3 on 3, 4 on 4, 6 on 6, 7 on 7 and 8 on 8.
shield ground is on 1 side only on pin 5.
I use 3 TDIF wires between DM4800 and X48.
then on the DM4800 you have to go to remote menu (alt + remote) then machine control, then you choose option 4 MM / MX24 / X48 in the right list.
In the STATE column at left, you must have the double arrows sign, select chase + transport. Under REC, choose 1-24 (I have not try others) and push enter and it's done.
on the X48, go to settings / Prefs and under Sony 9-pins choose track/arm = digital console.
note that in this config only the tracks 1 to 24 can be record armed.