By now I've found no way to customize or even translate the Help Center page (../jira/servicedesk/customer/portals). This makes it impossible for us to roll out SD to our customers.
We need a customization of colors, logo, headline (Jira Service Desk), title, texts & links
Thanks so much for your votes and comments on this issue.
JIRA Service Desk 2.5 has been released with the ability to Customize / Translate Help Center and we all hope you take it for a spin! JIRA Service Desk 2.5 contains lots of other goodness and you can read the full release notes here.
JIRA Service Desk Product Management