There is a bit of confusion going on here, but let me try to clarify things:
Lets say you wanted sql that looked something like:
SELECT
`main_table`.*,
`main_table`.`email` AS `invitation_email`,
`main_table`.`group_id` AS `invitee_group_id`
FROM
`enterprise_invitation` AS `main_table`
WHERE (
(status = 'new')
OR (customer_id = '1234')
)
In order to achieve this, your collection needs to be formatted like this:
$collection = Mage::getModel('enterprise_invitation/invitation')->getCollection();
$collection->addFieldToFilter(array('status', 'customer_id'), array(
array('status','eq'=>'new'),
array('customer_id', 'eq'=>'1234') ));
Now to see what this looks like you can always echo the query that this creates by using
echo $collection->getSelect()->__toString();