Hi Damon!
You should simply specify address value to correspondent CustTable fields and call CustTable.insert() method. If you look into this method you will find the code which is caring about Global address book data consistency:
X++:
// Check if not associated to Party
if (!this.PartyId)
{
// Create a Party entry for customer
this.PartyId = DirParty::createPartyFromCommon(this).PartyId;
}
else
{
DirParty::updatePartyFromCommonInsert(this.PartyId,this);
}
Best Regards!