well, if they're on different subnets, that won't work.
grab a laptop or desktop, and set its network info to a static ip address of 10.0.0.100, subnet 255.255.255.0, you can leave the gateway blank.
after that's done, you should be able to browse to
http://10.0.0.50 (the lexmark)
set the lexmark's ip address to some unused ip address on your 10.10.100.x network, with a subnet of 255.255.255.0, and your gateway of 10.10.100.x
save the changes, it'll reboot. at that point set your laptop/desktop back to what it was before, and tell the server the ip of the lexmark. you should be good to go at that point.
