I think F5's perspective on using the persist command with explicit node or pool member selection is that the iRule should handle the persistence if it's handling the load balancing. So I think it will be a bit of an uphill battle to get the LTM behavior changed. You can manually set a cookie for persistence when you're manually selecting a pool member following the logic outline in this post:
http://devcentral.f5.com/Forums/tabid/1082223/asg/50/showtab/groupforums/afv/topic/aff/5/aft/1166691/Default.aspx1166717
As for UIE persistence in an iRule or a profile, I'm not aware of any functional differences. You don't need to add a UIE persistence profile in order to use a persist uie command.
For the persist cookie insert command, the only available options are 'persist cookie insert < name > < timeout > ' where is optional < timeout >.
Aaron