First, I would like to thank you all for the feedback. At last, I managed
to get them active.

BUT, as there is always a but ;) , I can't manage to get ttyE0 to 80x50 at
bootup (I configured the wscons.conf to set them up during boot)
Also, I can't enable scrollback (shift-pageup shows escapes, maybe it's
another keystroke under bsd?), and haven't found any infos on that (maybe
a terminal other than vt100?)
AND, in man pages, highlighted text is shown as gray on brown, which I
guess isn't exactly as expected (maybe yes?)
Is there a way to get mouse running other than X? (gpm?) I found a man
page on wsmouse, but there is no such command, or maybe I don't know
where to find it.

Thanks for the patience!