> Based on my reading, I know I need to have Qualtrics generate unique ID
Qualtrics generates that ID automatically. You do not need to instruct it to do so explicitly.
> But, how do I get that URL query parameter?
As detailed in the Qualtrics documentation, the variable in Qualtrics that holds that id is called ParticipantID. You need to forward the value of that variable to the Inquisit launch page in an URL query parameter as detailed under the heading "To pass information from a survey:" at
http://www.qualtrics.com/university/researchsuite/developer-tools/api-integration/passing-information-through-query-strings/> I also understand that I need to enter that URL query parameter while I am setting up the Web Script Wizard. But, where
> exactly do I have to put the information?
In the example in the Qualtrics documentation topic above, the query parameter is called "ID". You can either use the same name or call it something else. The important thing is that you enter whatever query parameter name you have chosen in Qualtrics into the Inquisit launch page: The launch page must know the name of the query parameter it is supposed to read out and use as subject identifier.
> Again, how does the URL that is supposed to be entered during the Web Script Wizard look like?
This is something Qualtrics support ought to answer. I do not know whether Qualtrics has the capability to pick up a survey where it has been left off after redirection to another site. It may be that you actually need to set up *two* Qualtrics surveys, as in
#1: Pre-Inquisit Qualtrics survey
#2: Redirect from #1 to the Inquisit launch page, include the Qualtrics ParticipantID as query parameter
#3: Redirect from #2 to URL for post-Inquisit Qualtrics survey. Have that survey read out / use the same query parameter such that all three components (Qualtrics survey 1, Inquisit IATs, Qualtrics survey 2) use the same participant identifier.
The way to have Qualtrics read in information from query parameters is also covered at
http://www.qualtrics.com/university/researchsuite/developer-tools/api-integration/passing-information-through-query-strings/ , under the "Passing Information Into a Survey" heading.
Hope this helps.