I've resolved my problem :);
I use gctpc (gctpc is mentionned in commentaries of proj.js) for create
Mercator_1SP's init, inverse and forward functions in the proj.js.
I needed this projection for my project so if You think It can be
useful for someone I can commit it (but I don't know if I 've svn
commit access on this file)
I call this projection EPSG:9804 but like said Franck, It's maybe not
the appropriate name.
What do you think about that ?