From what i understand from a course last week, only certain FMS types will permit 0.1 0.2 etc, others are stuck at 1.0 2.0. So quite possible 777 FMS won't do what you are asking.
Can I ask why you are trying this in RNAV, GPS, or RNP ? If the goal of these procedures is to increase accuracy, isn't your idea of offsetting working against that?
Offset for cruise, SLOP is a different thing.