How do I save array (checkbox) values in a custom component?

I'm hacking up a new element based on the grid.
Instead of radio buttons, I am using checkboxes.
Instead of a single value, checkboxes return an array.

The saving function can't cope with that, I don't see a way to serialize my data before it goes to be saved
One approach is to serialize the database field.
$tables['webform_submitted_data']['fields']['data']['serialize'] = TRUE;
However this will have other knock on effects I'm sure.