In ProcessFlow 9 (this was updated in v 8.1, but I don't know anyone who used 8.1) you no longer have to default the application product line like you did with previous versions using WF00.

The application product line is now a criteria field on your Service so that you can enable your Service for only one product line or for different product lines by copying the Service (this allows connecting it to a different flow file by product line).

If you don't default a product line your Service will work with as many product lines as you've set up to use ProcessFlow. (Some of the enable flags, like with Match Company for cost messages still refer to ProcessFlow as WorkFlow).
If you're using Design Studio to create your ProcessFlow Inbasket displays, you aren't limited to a Formlet, you can use a Data Query.

Here's how to include select criteria from the variables in your flow so that only the data you want will be displayed:

function data0_OnInit()
// create new variables and reference the variables from your flow (page.parameters.FLOWVARIABLE)
var myVen=page.parameters.VEN
var myInv=page.parameters.INV
var myItem=page.parameters.ITEM

// data0 = your Data Query name
var dmeObj = page.objects["data0"];

// pass your variables as Select criteria to your Data Query
dmeObj.criteria += "SELECT=VENDOR%3D" + myVen + "%26INVOICE^%3D" + myInv + "%26ITEM^%3D" + myItem