Triggering a ProcessFlow from Portal Page Designer?

I am a little confused about your question. Within processflow to kick of another flow you would use the WorkObject node, Are you asking can you use a WebRun that executes a portal page? (http://yourserver/lawson/portal?_URL=). Are you trying to add workunit variables to a flow? What are you trying to accomplish specifically.

Actually, I am new to Design Studio, just got it yesterday, and wrote a terrible explanation. So, I want to launch a Process Flow we created and pass it some values. I have Design Studio to create the parameter form but it looks like I have to start from an existing form - is this correct? I can't start my own blank form with a new token number?

If you are trying to use the UI Designer wizard for triggering a flow, yes it has to be based on an existing form, it can be a custom form but it has to already exist in pgmdef.  You could conceivably use something like HR00.1 and, hide all the fields and default company number to an existing value, then by removing all the function codes it would be like creating a new "token" so to speak. You can create a trigger from a portal page without a formlet by doing an http request with a Web Page or Image node using an AGS call to WFWK.  There are examples in the back of the Design Studo user manual on how to write a trigger this way.  The Image node would give the click ability like a button.

Thanks. I saw the image trigger but how would the user enter parameters in a Portal Page - it looks like there are no input boxes?

Yes, it would not be practical to use a Portal Page for that reason, you are better of building a Formlet, or writing it in HTML like Self-Services.