Blacknor Hole, Portland

[tim.rose2]

Anyone know if the climb up to either of the Blacknor entrances is bolted?  I know where the old abseil point is on the cliff path above and the path which leads to the bottom, however is there an easy way to identify where the hole is looking up as the entrance is obscured from below?  Obviously I can have someone dangling something over the top whilst stood below if required.
Cheers
Tim