Yes there is a method to put some text on the application portal page in CAM.
Adding the following CSS to the theme.cc file (which can be downloaded from CAM by going to settings - customize appearance - check the 'enable advanced customization' box) will add the text in the 'content' attribute just below the 'personal' applications header.
content: "legal disclaimer text";
The CSS content property does not allow for HTML input (e.g. the JS innerHTML equivalent).
JS injection methods are not available.
Enhancement Request 694133:Customizable Application Portal has been submitted to Development for consideration in a future release of One Identity Cloud Access Manager.