raintiger,
August is not a good time for Boracay, the island faces west and the habagat (southwest monsoon) beats it pretty hard until October. I was in Boracay 3 years ago in August and the only diving is on the back side (not the best bits) of the island and the weather is always rainy and not very pleasant.
Other parts of the Philippines do not suffer as bad as they don't face west and are more protected. PG should be OK, but you said you have been there and want to go somewhere else (PG is a favor of mine, I personally would go back there). You can try Bohol (Pangalao Island) and Soutern Leyte, I've been to both in August (same year I was in Boracay) and they are diveable at that time.
Transportation to either Pangalao or Southern Leyte should be easy from Dumaguete, you should be able to get an Oceanjet ferry to Cebu and then take another Oceanjet to Tagbilaran, Bohol (1.5 hours) or Hilongos, Leyte (2 hours). Oceanjet has a website,
http://www.oceanjet.net/.
From Tagbilaran its about 45 minutes taxi ride to Alona Beach on Pangalao Island (Pangalao is just across causeway from Bohol). Alona has a nice white beach and several choices for accommodation and diving. Balicasag Island is just offshore and a great dive site.
From Hilongos Pete's Dive Resort (
www.whaleofadive.com) can arrange for you to be picked up, I seem to recall drive is about an hour to Padre Burgos, Leyte where Pete's is.
If you still want to go to Boracay, the fastest/most expensive way will probably be Oceanjet ferry to Cebu and then catch a flight to Caticlan (nearest airport to Boracay). I don't think their are any flight connections between Dumaguete and Cebu, but you could fly Duma-Manila then Manila-Caticlan
Cheapest/slowest way will be bus/jeepney up to northern Negros, ferry to Panay (not sure how habagat affects ferries) and then bus/jeepney to Caticlan.
Hope this helps and enjoy where ever you dive,
Drew