Datamapper | m:m + join_fields edit form

[eluser]Anestetikas[/eluser]
Hi,
I'm having some problems with making a good edit form to work with datamapper.

For example:

I have a table "Cars":
id, model, registration_number

and table job:
id, name, description

Also table for many to many relation:

cars_job:
id, car_id, job_id, due_date

I want to make a edit form for my cars where i could also manage all possible jobs related to it.

If it would only be m:m I could use multiselect, but here I need some kind of checkbox+input field (for due_date) combo.

How should I approach this?