The data entry is the same as for ratio pricing, except that you select Roll from the drop-down box instead of Price (just like for premium based contracts).
Under the Risk tab of a ratio priced contract, select the light blue area to edit Rolling/Pricing.
You can change the quantity to a lower amount (default is max) and change the number of lots (default is calculated).
For premium-based contracts, there is a field for the rolling price (used to calculate an adjusted premium). For ratio-based contracts, that field is used to manually enter the adjusted contract ratio to apply for pricings in the rolled period.
When the rolling is saved/applied, the same hedge requirement is created as for premium based, but based on the number of lots specified by you.