can this be done? The destination server is a Novell Groupwise WebAccess. The login window is a standard HMTL form. Can I have the SSL gateway parse this page somehow and submit user credentials automatically?
Yes and no. For this function look at SSO FORM Post in the Role.
The No is for "he SSL gateway parse this page somehow".
You will have to define for what page this rule shall be applied (the URL displaying the loginform), to which URL to post (form's action), and which fields + values to post. The username and password may be taken from the internal vars.
I've done this for the login forms of our Novell iChain, which worked fine. Therefore I also posted the hidden fields, happily the values were static