Here's a quick guide I wrote to help everyone:
1) Click on "Email erstellen" - this will load up the website in new page containing your 'temporary' email.
2) Copy/paste the email address into "Email hier eintragen".
3) Type in a username/password in the relevant area ("Login Name" & "Passwort") - NOTE: If you click on the dice it will generate a random password for you.
4) Click on "Account Generieren" - wait for it to complete.
5) Now refresh the website that was loaded previously (your temporary email account) - you should see an email from free.xennews - click on the link inside to 'activate' the account.
6) Now type in the details into your news server client and away you go! :)
Thanks again to boltonguy2k for sharing the software - and to the author(s) of the software for making it so easy! :)