Hi there
I too am yet another Streamyx user with the exact same problem (living in Malaysia). I can not access LimeWire or itunes Store anymore as at December last year. After nights of researching on Google I discovered a forum abou the connectivity problem with Streamyx and itunes which happened the same time LimeWire couldn't connect anymore. From what I am reading, it seems that during the re-routing of the Streamyx servers after the earthquake something hasn't been configured properly on their end and it has blocked several P2P's. I can use UTorrent without a problem though.
Obviousely Streamxy have no idea what is happening on their end as I also read that some are able to connect to LimeWire and iTunes through their work Streamxy connection but not their home connection.
This site
http://forum.lowyat.net/topic/400109 has suggested setting up a Proxy and connecting iTunes through that. I haven't tried (because I can't work it out) but it seems to work. It may also work with LimeWire if your lucky.
If someone gets this going and is successful please let me know and maybe post the exact steps you went through to set up the Proxy. I am not that computer literate and the explanations on this post are not very specific I'm afraid but the people who are getting it seem to be getting success.
They also mention that they are able to connect to iTunes at Starbucks but not at home. Will try with LimeWire tomorrow.
Good luck.
P.S. Aparently Celcom don't have this problem but don't quote me on that.