The odd thing about COx is that they don't pick on everybody. I assume as soon as they detect you both downlding & uplding much more than the average surfer then you may come to their attention whereby they will filter your speeds. They not only apply this principle to LW but also other p2p clients. The question is do they use a p2p detection softw. If yes then their might not be a simple solution.
Possibly worth a look at are:
A Fix for those whose ISP's block Limewire pages 1 & 2 which has a link to alternative instructions.
Another Insight proxy solution http proxies A Successful http Proxy Solution