Passing parameters in Reporting Services

I've spent hours researching this, and have come up empty. Hopefully, someone here can show me that this can be done.

I am using Reporting Services to generate a large report from an even larger database, on SQL Server 2000. I am going to give a generic example of something I'm trying to do. I have a query:

dataset => SELECT mydata FROM mytable WHERE myval = @param

The data that this query generates is being used by several cells in my report table. The only difference between each cell being the value of @param. Now, obviously, the long way of doing this would be to have something like:

dataset1 => SELECT mydata FROM mytable WHERE myval = 1

dataset2 => SELECT mydata FROM mytable WHERE myval = 2

dataset3 => SELECT mydata FROM mytable WHERE myval = 3

etc, etc. The equation for each table cell would then be something like:

= SUM(Field!mydata.value, "dataset1")

where I have to have an explicitly defined dataset for each cell, as above.

What I would *like* would be to have a generic dataset (first dataset above) that I could pass the value of the parameter into in the report. For example:

= SUM(Field!mydata.value, "dataset?param=1")

or

= SUM(Field!mydata.value@param=1, "dataset")

or whatever the particular format would be.

Now that I've given this long-winded explanation of what I want--is this possible? Like I said, I've looked high and low for an answer, and nothing I've seen even hints that this can be done. Am I SOL? Am I just blind and the answer has been right in front of me the entire time? I'm a little desparate, as the report beta is due the 26th, and I really don't want to have to spend the time creating individual datasets for each param value. It literally means the difference between 100+ datasets and a couple dozen.