David,
You might want to look into Dennis Brown's Flexible
Parameters.
He has built quite a nice interface that is relatively easy
to use. Like all thigs, your mileage may vary, but check it out and see if it
fits your needs.
I think it can be found in the user KB, and possibly
in the files.
I know he is working on a "soon" to be released updated
version, but I am using 4.2 and it works fine for what I
need.
Blair