User access to limited irules.

Yes, you can create a new partition called A and create a new user with role iRule Manager and just select this A partition.

As for moving the existing iRule configuration. If you are pre TMOS 11.6 then the only way around this is to delete the iRule and recreate in the new partition or edit the bigip.conf file via SSH. If you've 11.6 then there's a new feature to move objects. See 11.6 release notes and the section "Object move and rename". I've not used this feature myself so I'd test first.

Hope this helps,

N