Bill, there is a fee for looking up birth entries or for obtaining certs, and as you have the exact dates - but not the place - the easiest and most accurate way of getting information would be to buy the birth certs. These have name, date, and place of birth, father's name and occupation, mother's name and maiden name, name of the person who reported the birth, date of regt.
Write to the Registrar General, Deemsters Walk, Bucks Road, Douglas, or email: http://www.gov.im/registries/general/civilregistry/welcome.xml
Give them all the information you have, including guessed place.

Sue