Isync, .mac Synchronizing With Proxy

[BBx]

computer #1: Power Mac G5
computer #2: Powerbook G4
valid dot mac account

Both machines running OS X 10.4.2 and iSync 2.1;

Here is my problem.

I am attempting to sync the Computers and dotMac accounts Bookmarks/Calendars/Contacts/Keychains/Mail accounts/Mail rules Signatures and Smart Mailboxes.

Everything is syncing up fine until I switch both computers to use my https web proxy instead of a direct internet connection.

Is there a way to tweak network settings to be able to access my dot mac account and to use iSync 2.1 as advertized?

Some advice would really be appreciated, Thanks