how do you unlock an htc shadow with a mac running osx 10.5.4 leopard?

i want to buy a shadow, but the company i want to use for wireless is not t-mobile. Found a locked t-obile phone on ebay, and want to unlock it in order to use it on the other network. They gave me a cim card and said if i can get the phone to work then i can use it on there network. How do i unlock it? I have a mac, but have access to windows if necessary.
thanks
mike

I suggest you can approach Prounlocking.com and specify the country,locked network of HTC Shadow.Based on the availability you can get the permanent unlock code along with free instructions.