In theory, assuming you have an SSL certificate installed, you can add these to user.config, recycle the app, and then mojoPortal should be able to detect correctly whether a request is secure or not and that should enable mojoPortal to force SSL on pages that require it.
<add key="SSLIsAvailable" value="true" />
<add key="SecureConnectionServerVariableForValueCheck" value="HTTP_CLUSTER_HTTPS" />
<add key="SecureConnectionServerVariableSecureValue" value="on" />
the 2nd and 3rd settings are based on the rackspace article.
This solution was implemented for web farm support of SSL but has not been well tested since we don't yet officially support web farms, so your mileage may vary.
Hope that helps,