Is it possible to use the {*USERNAME} variable with link in Templates...
Like this:

<li><a href="/profile.forum?mode=viewprofile&u={*USERNAME}&page_profil=friends">Link</a></li>

but this doesn't work, any ideas?

Maybe this link can help you -> http://www.avacweb.com/t125-8-variable-in-html-pages-and-templates

This doesn't work with links.

I think you have to contact LGForum..

The tutorial does provide a way for using it in links.

No. It doesn't work.

I found a very good topic for use the {*USERNAME} variable in Templates, I advise to take a look on it, here
http://forum.dion-designs.com/viewtopic.php?t=440