Can you provide more information on what you're asking ?
If you are asking whether its possible to change the Content Style Sheet - then yes, its possible to change that. An example is the color of the header or the layout of the initial login screen.
If you're asking about a specific application within E1 - then you'll have to do that in the JDE Toolset as the code is interpreted at runtime, and what you "see" is how the form is being generated each time you open the form. There is no HTML to change, as it gets generated each time in effect...
Provided you're at a tools release where you can call out a task in an E1 Page generator DAT file, try the following:
1. Create a task (e.g. called TESTURL) and assign it to a URL
2. In your E1 Page, add this task in your .DAT file with a line like: @A:task=TESTURL
3. Run the E1 Page Generator and publish your E1 Page
Now if you want to change the URL, just go into the task (Task Revisions) and change the URL there. The next time you log in the E1 Page link will point to the new URL. Note you may want to clear jdbj caches (esp. menu cache) first.
I think the short answer is that NO you cannot change the link. An E1PAGE is contained in a .zip file that is stored in a blob. you cannot easily manipulate it without modifying the .dat file, regenerating the page with the generator, and re-uploading the page.