Jan,
Yes, as I could read you are a bit overbooked... No problem for the implementation, in fact, my mind was to develop it for 'the community'...
When I first post, the development was very 'hard coded', and very specific.
Last 'night' (because, I have also a 'day life work'...) I started to make communicate your component with another one called ChronoForms /
http://www.chronoengine.com/.
The advantage is to have 'unlimited' form design possible, and a very strong forms management backend.
After a long night of ajax tricky things, and headhack

with forms submissions, response encoding, it works 'almost'...
I tried to develop this less obstrubtive as possible for the phocaDownload Component and chronoengine one.
The advantage for your component, is that 'hack' is very soft - regarding the code - and could be easyly releasable for you.
(the end user have of course to install chrono form on his joomla site).
So, when I said 'almost', I have a last 'auto form submission' to do, and a very little patch on your admin section to add chronoform list as 'licence agreement extenssions'... As I had a lot of very bad surprise while coding my little 'hook', I can't says 'yes it works' right now, but... I hope I could do it...
Here is another screen capture :

Could you give me an email, so as soon as it works i could send you my 'repackaged' phoca download component.
Cheers,
Eric.