XSane 0.99x : how to setup scanmode to black and white?

[charlie6]

Hi,
according to the Xsane scan options documentation, see here
http://www.xsane.org/doc/sane-xsane-sca ... s-doc.html
there are 4 scanmode options: color/ grey/ halftone / and lineart , this last corresponding to black and white.
On puppy live-cd's, Xsane is only featured but with color/ grey.
I wanted to get scanned files to B&W as they need less MBytes..!
examples:
one A4 scanned file need 0.6MB grey / 1.6MB color under 75dpi res.
If one does not needcolor nor grey, under B&W it needs only ±200MB.
How then to get 'lineart' option?
Is there ant extra-pet to install?
Thanks for any advice !
Cheers
Charlie