Need Help! Fanuc G10 use

Hello,

I have used G10 to load G54,G55,G56 & G57 registers with X-axis values to move the coordinate system in X for feeding extruded aluminum on a VMC machining long A/C stringers longer than X-axis table using the following program code:

N3 G10 L1 P1 X0 U30.5 Y0 Z0 A0
N4 G10 L1 P2 X0 U30.5 Y0 Z0 A0
N5 G10 L1 P3 X0 U30.5 Y0 Z0 A0
N6 G10 L1 P4 X0 U30.5 Y0 Z0 A0

What I want to do now (different machine) is incrementally shift the Z-axis of the machine coordinate system (G53)
using the G10. I want this to also shift all the other part coordinate systems. The Fanuc manual is unclear on the
L and P values to do this. I am quessing:

G91 G10 L1 P0 Z6.5 (P0 is register 0 (G53), Not sure about L, Z6.5 is the shift amount Z+ )
G90 (re-establish absolute mode)

Machine coordinate system will be returned to zero at the program end.

Any experience with using G10 to load or change machine coordinate system G53 would be helpful.

NC4EVER,
Larry