Re,
 
 Guillaume, I can't edit the login page's access write's. If I login then try to get to the login page, it fowards me to the wiki home page. So I can never get to a position where I can change its access writes.

 
Before overwriting albatross, let's try this last step :
  1. Go to http://<server>/xwiki/bin/edit/XWiki/XWikiLogin?editor=wiki
  2. Add this code at the top of the page above any other content :
    1. #if("$!request.skin" != "myskin") $response.sendRedirect($doc.getURL("view", "skin=myskin")) #end
  3. Click on Save & view
  4. logout, then try to login again.
Actually the solution I suggested doesn't work, but here's one that does :

Go to your xwiki folder on your filesystem -> go to webapps > xwiki > templates & open login.vm in a text editor.

In the file, replace

#else
###
### Login page
###
###

with

#else
#if("$!request.skin" != "YOURSKINHERE") $response.sendRedirect($doc.getURL("login", "skin=YOURSKINHERE")) #end
###
### Login page
###
### 

 
Save the file & try to login again -> you're done :-)

Guillaume