No qualifications on the Jill apart from them being female.
2 riders (1 jack, 1 jill) set off together on the normal TT course, time of the jill across the line stops the clock.
If you've got a faster jack then being a gallant gentleman he should set pace with jill tucked in behind him enjoying the draft until the last moment when jack moves aside to let jill take the line and glory. If you've got a slow jack you may have to kick him a bit or even get on the front yourself and show him how it's done