FormsCentral (and the other Acrobat.com services) are not available as a locally-hosted product, you have to access them on Adobe's US servers.
Any other suggestions?
I'm not sure if this would work but you could export the submission enable PDF form (available under the Destibute Tab if you have a PAID subscription) and host the PDF on your server. People will have to download the PDF to their system and fill it out using Adobe Acrobat or the free Adobe Reader (desktop or mobile version). Now they will still need to be able to post the data to FormsCentral so they might still have firewall issues when they submit the form. Also note that not all FormsCentral features are available on PDF forms (e.g. no skip logic or attachment fields)
The other option would be to not use FormsCentral to gather/manage the data. Create the PDF form in FormsCentral but then use Acrobat to change the submit button to email the PDF directly to you (instead of sending the data to FormsCentral). You will then need to manage the data yourself. Let me know if you need more information about this. You will need to have access to Adobe Acrobat (which is not the Free Adobe Reader) to be able to make the modifications to the PDF. Fillers will still be able to use the free Adobe Reader to fill out and email the data to you.