Stephen, Alan et al,
This was something I briefly looked into doing sometime, had we not seen the species recently off its annual but not common occurance in the warm waters off North Carolina. Infact I would still potentially do it.
Have a look at this fascinating footage of the species. The first part of the video shows its possible to do them by boat and the final part sort of looks like it may possibly have been shot at dusk on or near the breeding island. There are two email links, and the film makers may be able to provide more detail. If someone does contact them please post details on here, not least to stop them being harrassed.
The place to see them would be from the southern tip of coopers island. It is a nature reserve in Castle Harbour and the birds breed on the off shore islets. Multimap provide good arieal coverage: http://www.multimap.com/maps/?hloc=...,-64.65278|16|32&loc=:32.34748:-64.65292:18||
If you can get there I think you should hopefully see the petrel at the right time of year (and day!). They want to make it into a visitor centre I think. A potential problem may be access, it is a former US military site, but there seems to be some access. See also on this point the IBA factsheet http://www.birdlife.info/wbdbwebstaging/SitHarnessDetails.asp?sid=19779&m=0
Although it may be a little out of date now. Boats are the another option as mentioned.
White Tailed Tropicbird also breed in the area.
By the way the North Carolina pelagics on the Stormy Petrel II are well worthwhile. We did 6 in the last week of May/early June this year and saw Pterodromas
every day, mostly black capped petrel, but 2 'Fea's' and a Bermuda. http://www.patteson.com/