You can't use parameters that way (at least I've never seen it), but you can probably do something similar with blending.
You're goal isn't 100% clear to me (do you want people to edit the wegiths?), but you could create these fields in an Excel (or custom SQL) data source and create a dummy blend field that is the same for all values in the main data source. Something like
Now your formula is
[Budget]*[Weights].[People] + [Budget]*[Weights].[Hours] / [Budget]*[Weights].[Tod]
If this isn't quite what you're looking for or isn't clear, maybe you could post a sample, packaged workbook.