I've made a few internal improvements to the way that MrsWatson handles command-line arguments, including adding support for specifying an argument multiple times. The new --parameter option takes advantage of this:
mrswatson --plugin something --parameter 0,0.75 --parameter 1,2.5
There is no theoretical limit to how many times parameters like this can be given, though in practice very long command lines are limited by the operating system. I've been thinking about supporting JSON files for the plugin chain configuration, since this is a logical data format and this particular part of MrsWatson can lead to very hairy command line arguments.
Also, the next version of MrsWatson will no longer have separate options for setting the time signature numerator/denominator, instead a new --time-signature option allows one to pass strings formatted like "2/4" to the program instead.