Hi,
You can use the getresults X-Function to get the parameters. Take your simple example here: In the Before Formula Scripts text box of Set Column Values dialog, the following two lines are used to get the parameter y0.
getresults tr:=tr1 iw:=[book1]FitNL1!; // book name here uses Book1
double y0 = tr1.parameters.y0.value; // get y0
Then in the upper text box of the Set Column Values dialog, type: y0*col(a).
Penn