Correct!
Dead a/c. Start the apu ...the D.C. pump runs.
A.C. power ON the l/h aft BP runs and the D.C. pump switches off.
To run the APU from the r/h main. Switch ON the r/h aft BP. OPEN the crossfeed valve(s) then trip the l/h aft BP circuit breaker.
Don't forget to log what you've done regarding tripping of CB's! 
I can't be sure of this but if the APU is started and the AC and DC pumps do not operate, the APU fuel pump may be able to suction enough fuel to start.
Also correct....up to a point! If you are lucky enough you may just get AC power on in time, otherwise it's look for suitable access to get up there to bleed the FMU
That certainly applies to some other Boeings!