Hyperlink in a User Exit for standard transaction?

Hi,

First off, I am a novice in ABAP. After some searching on the forums, I have found out that it is possible to have hyperlinks in an ABAP Programm.

Is it possible to change a standard transaction (through user exits) to add in this sort of functionality? For instance, a link in VA23 to jump to a remote portal? Is it possible? And if yes, could anyone give me an example of how this could be done? Links to documentation or tutorials would also help me.

Could such a functionality be added through a button in the same transaction instead of a simple hyperlink?

Thanks and regards

Sameer