First, I am an Ariba newbie. 
We are looking to integrate our existing web application, that allows buyers to purchase services, with Ariba. Due to the custom nature of our services, we have determined that using a PunchOut catalog makes the most sense. I am reviewing the cXML Solutions Guide and I've read a few other documents in the Ariba Production Documentation site. I believe I have a test punchout catalog setup in our test account. One of my initial questions is how can I work with this test catalog pointing it to a development version of our web site on my local machine? It appears that SSL is required even in the test account. Can I use a self-signed certificate?
The existing web application that we will be integrating with is ASP.NET application written in C# running on IIS.
If this is not possible, how can I simulate cXML transactions being posted from Ariba to our application when we are developing our solution?
Thanks,
Chris