X and Fluxbox :: Xinerama

It's several days i'm trying to resolve some "two monitor" issue, and now i'm trying to get two monitor (one plugged into sisusb device) with xinerama

googling here and there i found an hint: xinerama works only if wm support it

so...

does fluxbox support xinerama?

and, xfree86.dsl for dsl, work with usb device too?

i know is silly question, but i don't what spend time in something is not supposed to work