Do you mean wire up a male plug to the scart socket on the monitor or that the monitor doesn't have scart sockets and you want to add them on?(i'm guessing you mean the second?)
If it takes rgb its not really necessary,as you can make bnc cables as easily as you can make scart ones....if you have a heap of scart cables you could make a scart to bnc adapter easily,and save having to lob of the ends of you scart cables.
If you want to wire it up internally it wouldn't be that hard either,but since you'll only be using around 5 or 6 of the 21 pins it seems fairly pointless,to hack up your monitor and add one...unless you're like me and like to hack up things for the sake of
BTW do a search if you want the pinout its not hard to find or figure out but remember that the composite video/sync pins are swapped for input and output depending on the connector....best to just wire them both up to the video in wire.here's the wires that are needed:
video in/out(join them together)
ground(any..you should only need to wire one up as they're usually connected internally)
That should be it,a lot of those pins are used for nothing except for in special cases..like the communication lines.You shouldn't need audio either unless your monitor has a a speaker.