how to expose custom date field to the views module?

Hi,
I have a module which provides an extra form field on the node/add form for content types which is of $form type 'date_select'.
when the node is saved i am writing the date to a custom database table.
I want to be able to have this field exposed as a filter and an argument in the views module, is there anything in the dateapi which allows me to achieve this easily? please note, i know this can be done by adding a cck date field to the content type but i do not want to use CCK to achieve this.
My date field does not seem to be getting picked up in view options under 'Date' as one of the checkbox options listed.
I have been able to add a custom filter through using views api functions, but it would be much better, if i could somehow just hook into the already exposed date filter / argument which is in views, and somehow 'register' my field as one of the checkboxes to choose from.
any help appreciated, thanks.