Probe your G54 bore, then:
#5241=#5221 (G55 X = G54 X)
#5242=#5222 (G55 Y = G54 Y)
#5261=#5221 (G56 X = G54 X)
#5262=#5222 (G56 Y = G54 Y)
Continue on to probing your three Z depths, then the main program.
Attached is the OMP40 manual, assuming that's what you're using.
EDIT: Holy hell did I screw that up! I read your post to have G54, G55 and G56. Whoops. Just alter the variables used with what you find in your machine manual.