Sorry for my stupid post above, ist much easier than that. Fortunately my axis to adjust was y. So here my code from my homeall.g
G91 ; relative positioning
G1 H1 Z200 F1200 ; move quickly to Z axis endstop and stop there (first pass)
G1 Z-3 F150 ; go back a few mm
G1 H1 Z200 F100 ; move slowly to X axis endstop once more (second pass)
G1 H1 X-698 Y-355 F3000 ; move quickly to X and Y axis endstops and stop there (first pass)
G1 H2 X5 Y5 F6000 ; go back a few mm
G1 H1 X-698 Y-355 F360 ; move slowly to X and Y axis endstops once more (second pass)
M584 Y1 U3 P4 ;split y axis
G1 Y1.2 F100 ; drive y axis (drive 1) 1.2mm back
M584 Y1:3 P3 ;recombine drive 1 and 3 to y axis
G90 ; absolute positioning