Cannot get 3rd party usb ethernet adaptor to work

[weeyao]

Hi, anyone has experience trying to get a usb ethernet adptor to work? I got a non-apple product for a third of the price and now it will not work. I installed driver for it from http://www.sustworks.com/site/news_usb_ethernet.html but my comp does not allow me to edit the info.plist file although i set myself to read and write.
Please help if you can!