If you have the results page configured to search on these parameters you are almost there. You need to ensure that your results page is looking for the $_GET version of a variable to have it work properly. You can just update the values that are referenced in the DataAssist Search wizard to be $_GET instead of $_POST.
Once the results page is set to work with the get version of the variables you can then add in the URL parameter to the link itself. Here is an example of what this might look like:
<a href="thepage.php?catID=1&Search_x=1">link to the page</a>
This is just an example but the URL parameters that php sees as $_GET variables are specified in the URL after the question mark and ampersand. If you have any further trouble with this please post back with the results page in question and some example links from your current menu with information about the category.