Thanks for your help, mdekker...i will try as soon as I'm back on my test environment.
The output from a one-question survey (which I rerouted from the html form POST-command) looks as follows:
fieldnames=171217X171X1634&171217X171X1634=N&java171217X171X1634=N&relevance1634=1&relevanceG0=1&move=movesubmit&thisstep=2&sid=171217&start_time=1361740277&LEMpostKey=1502713047
So, first the fieldnames (which already come in the old SGQ-structure. Then the fieldnames and answers and then some logic-related and survey specific data. So I should be able to make this work, at least for smaller surveys.
There seems to be a lot of demand for an offline-solution for limesurvey. There are a lot of these freelancer-websites with such requests and offers. Unfortunately none of them have made it into the official limesurvey code.