Macro for Solver with user defined changing cells
 

I have created a little calculator that caclulates the values of
different parameters if I want to achieve a goal e.g. want to have
total costs = 0. This is done by using Excel Solver.

I want to create a User Form with many click boxes (number equal to
the number of chaning parameters in the calculator) where the user
will have the choice to choose which parameters will be included in
the Solver by clicking in the appropriate box.

The problem is how I write a macro that I can link to the Solver Macro
where the "changing cells" in the latter change according to the
choices that the user has made on the form.

I hope it makes sense what I want to do and I hope there is a solution
to it. Many thanks.