The two modificators that I know are for solve a problem or for delete the results of a file. But the Mecway files are "simple" text files (xml format as far as I know), so you probably could write it from Matlab and then send the commands to solve the problem.
I would work directly with CCX files in this case, have made it for material parameter determination time ago.
You can call it using the system() function within matlab. What you want to make sure first is that your .liml file is absolutely ready to solve, then pass the solve argument to Mecway as part of the string you give the system() call. That's pretty much the extent of Mecway's command line interface.
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I would work directly with CCX files in this case, have made it for material parameter determination time ago.