> But using Checkboxes doesn't work, I've tried putting them with the
> same name but all that appears is a string of the LAST selected
> checkbox :S. ?

I think you need check boxes here. html allow you to create many check
connected with the same name.

<input type="checkbox" name="options[1]" value="1" />Value 1
<input type="checkbox" name="options[2]" value="2" />Value 2
<input type="checkbox" name="options[4]" value="4" />Value 4


the submitted ones should appear as an $_POST array:
[options] => Array
(
[1] => 1
[4] => 4
)