Update here - using Macropump.m1s may solve the problem.
'Macro for target coordinates
'
Option Explicit
Dim XPOS,YPOS,ZPOS,XGO,YGO,ZGO
XPOS = GetOEMDRO(800)
YPOS = GetOEMDRO(801)
ZPOS = GetOEMDRO(802)
XGO = GetOEMDRO(196)
YGO = GetOEMDRO(197)
ZGO = GetOEMDRO(198)
SetUserDRO(1050, XPOS+XGO) 
SetUserDRO(1051, YPOS+YGO) 
SetUserDRO(1052, ZPOS+ZGO) 
Simply use the User DRO Variables 1050-1052 in your custom screenset, enable "Run macro pump" in General config and restart Mach3. 
BUT: the values may flicker and - especially on short tracks - don't represent the correct value...