No idea if it will work, i havent really tested it.
Say you have 192.168.1.0/24 on ether1 and 192.168.2.0/24 on ether2.
Server is connected on ether1, desktop on ether2.
Something along the lines of :
/ ip firewall dst-nat add dst-address=192.168.2.255/32 dst-port=137 protocol=udp in-interface=ether2 action=nat to-dst-address=192.168.1.255
/ ip firewall dst-nat add dst-address=192.168.1.255/32 dst-port=137 protocol=udp in-interface=ether1 action=nat to-dst-address=192.168.2.255
Add for all necessary ports of course.
Please let me know if it works or not