i already opened the script editor to see what mel command is executed. i saw that polyEditUV is used but
don´t exactly know how to get the min uv. the part after u must be the min/max value to what ist is aligned.

select -r pCube1.map[4] pCube1.map[6] ;
polyEditUV -r off -u 0.19682841;

undo gets:

// Undo: alignUV 1 1 0 0 //

these three bits seem to be for max/min u and v.