There are no reasonable options for this. You could in theory use VNC/Remote Desktop to access the B&W from the iMac, but I'm not sure how good the quality would be. Perhaps some sort of USB-based video input device like EyeTV, but it would be a real kludge to get the whole thing hooked up...I wouldn't bank on any sort of decent performance.
I'd recommend springing for a cheap monitor or seeing if you can find one somewhere.