What I tried to do was, to create a template and choose the import options
in a way, that Origin is able to import the data. The obvious way to put all
the parameters in the first row failed completely. The only solution I could
find, was to write all the parameters and some dummy variables in the last
row. It seems, that Origin needs at least in the last row some model data!
Unfortunately are my datafiles build in a different way! Is there a
another possibility to import this kind of datafile?

You can setup the template to skip the first row so the data will import
correctly.
The portion skipped is stored in the global variable %Z which you can parse
with substring operator and store the various parameters in a UIM status
object,
or store them in an extra column in the template.