I only know how to do this with a Verizon Wireless account and my LG VX8300, just FYI
1. Get an mlb.tv package (Obviously)
2. Go here and reprogram your phone to enable it's DUN (Dial-up Networking), by default it's disabled. Most verizon accounts have an unlimited internet package for about $5.00 more per month. after 9pm and on weekends the internet usage will not use your minutes, so these are the prime times when to use what i'm explaining. otherwise the internet package will use your calling minutes
3. Attach your phone to your PC via the USB cable it (should have) came with.
4. Install the drivers for your phone (Should be able to find them rather easily online, though for Vista 64bit which is what I use, it was a bit tougher)
5. Create a dial-up profile under your network connection settings, and name it something like Verizon or whatever. Use #777 for the dialing number, username will be
[email protected] (xxx=your area code, yyyyyyy=your 7 digit cell number), with a password of vzw
Once you're connected, browse to mlb.com and their system will not detect your current IP address as an Illinois ISP address, most likely an IP address located out of state wherever Verizon keeps their servers. I'm currently watching the sox game right now I'm unable to do this with my comcast cable account