A variable can be used to emulate a SETOFFSET like result for positioning. TO the idea of:

NUMERIC in_Left = 2.5
NUMERIC in_Right = 6.0
NUMERIC in_Offset
...
...
IF(side = left)
in_Offset = in_Left
else
in_Offset = in_Right
...
...
SETMARGIN (0.5+in_Offset)
SETXY $margin, 1.0
MOVE ia_TextString