No worries.
Yes you can do as you say and hit it with a crystal param.
I just wanted to make sure you knew you had to pull all data first (via a command, view or SP) which populates all of your crystal cascading param options, and then apply the selection of the params in the crystal select statement.
When you can pass a SP param directly into Crystal you can get some very nice efficiency gains because you are only selecting and pulling in the data you need rather than doing a pull of all the records, then a filter then presentation (as with crystal select statement).
Since you needed cascading params this boost in efficiency (using SP params directly) is not an option for this report.
Sorry for any confusion.