You have to 'add candidate' as usual, input minimal detail e.g. cover the current address for a full 5 years and press ROUTE 3 (click any 5 boxes and the birth certificate box).

When you get to POSITION - DISCLOSURE TYPE - NOT APPLICABLE then press the List 99 box.

It's a little bit long as it's normally done in conjunction with a DBS check but this gets round the system for you