I might be able to help you a little. We don’t run XPI on Unix, but on Windows. I doubt whether a certificate request should be generated on the server it will be installed on. The toolkit doesn’t come with the standard installation. We got it from the Webmethods website. If you have a Windows machine where you can work on, you can send an email to me and I send you the .exe and readme.txt. My addess is “patrick.kooman at vopak.com”.
Installing is easy. Goto the webmanager and, under “Security”, choose Certificates->Edit Certificate Settings. If you want to use the default names, (which I think is wise), you don’t even have to do this, I guess. Just copy the file to the shown directory/file.