This post has been hanging out unanswered for a while now. Hoping it's not too late, I'll venture a response. Normally, you wouldn't actually use Inquisit to achieve what you want. Instead, after a participant has completed your Inquisit web experiment, you'd redirect his browser to another web server hosting your submit form. So, you'd need access to a webserver with some SQL and/or PHP functionality and set up a HTML-form (plus maybe a database) to have participants submit or mail their contact data. I suspect that this is not exactly what you had in mind.
There might also be a way to mimick something like this solely using Inquisit: You'd need a total of 3 experimental scripts. (1) The web-experiment that you already have up and running. (2) A script presenting an entry form via the <openended> element or some survey-type question formats. Make sure to set
<data>
/ file = "mailto:youremail@yourdomain.net"
</data>
for the second script, so the data will be mailed to you. (3) A third script that does nothing but run the two other scripts in batch-mode. For example:
<batch>
/ file="webexperiment.exp"
/ file="submitform.exp"
</batch>
The third script is the one you'd have to register via the millisecond web interface.
Be aware that this approach will definitely compromise anonymity of your participants - if that's an issue. The subject id for all the scripts will be the same for a particular participant, so the personal data collected via the submission form could easily be matched to the collected experimental data.
Best,
~Dave