Push form-data before submission to PIWIK

Hey there,

I am looking to use PIWIK for a somewhat different task most of you people will use it for.
In the end it boils down to this:

I want to push data our (potential) customers fill in in our customer flow to an external service (Piwik in this case)
Our flow is extremely long (Cannot be shortened due to legal reasons, I work in the financial service industry) and I want my salesteam to have a chance to analyze & reconvince the abandoned formfillers.

I am “grabbing” the data using Javascript (before submission) and want to “output this data” to PIWIK on the fly.

Can you give me a few pointers/ideas on where to look in the overwhelming amount of information?
Any help is much appreciated!