As discussed, the marketing team needs to be able to track packages installed by users during the wizard.
The easiest way to do seems to be the loading of an iframe (which is not displayed by the wizard), and more specifically the page PackagesDownload. The list of packages can be passed in the URL, the name of the parameter or the list separator doesn't have much importance with Marketo.
I propose you the following format : http://www.nuxeo.com/Embedded/wizard/PackagesDownload?packages=cap;dm;collab
If possible, Roland would also like to know which os (win/mac/lin) is used. You can use something like "os" as parameter name, but it doesn't really impact the way marketo will detect it.