sorry steve that too wont work coz u need to operate on one of chains only. have alook below

[root@MDK10 firewall]# iptables -p tcp --syn --dport 80 -m connlimit ! --connlimit-above 2 -j ACCEPT
iptables v1.2.9: no command specified
Try `iptables -h' or 'iptables --help' for more information.