Thanks johnp. In fact, I wanted to use it for some devices since a long time, but it was broken in the two latest versions of coovachilli. This weekend I found a one line patch which correct this. So in order to make it working, you just have to update to coova-chilli-1.0.13-2.i386.el4.sme.rpm, and add the small template as explained in the wiki page.
Cheers, Daniel