Thanks again and sorry but I don't get what "top-post" means ... I guess it's about answering on top of history mails ?
I'm kinda new to mailing-lists...
 

Sorry for that too, I'm also new to Gentoo, and for an unknown reason, I trust it for a big project, so I must be sure of many things...
 

It's not clear to me on that point: is the "currently-being-built-stage-or-livecd" emerge used, or is it the "catalyst-running-host" emerge ?
 

After many doc reads, what you say now seems obvious to me. I must create a profile to specify base systems packages, and many "default" things.
My problem is that it appears that it cannot be done properly and easily : Catalyst requires a /usr/portage related profile path, but putting a custom profile here would kinda break original Gentoo portage tree.
I tried to put a custom profile in /usr/local/portage/profiles and specifying a "PORTDIR_OVERLAY" in my make.conf, but the profile didn't show up in "eselect profile list" so I guess Catalyst won't see it.
How can I tell catalyst to use my custom profile without putting "will-be-deleted-on-next-sync" garbare in official portage tree ?
I didn't found any doc on this.

Thanks in advance.