Well i havent tried the cab file that daddymike used.. But the Arcsoft one works fine.. Download and install cab on your phone. Go to Messages>All messages>Menu. Scroll down to bottom click MMS options go to CDMA servers Tab>Create new.
On server name put what you would like
gateway blank
port 80
Server address
http://mm.myboostmobile.com
connect via sprint
and sending limit put what you would like.
Press done
Save your new server as default and thats it.
I havent had any issues with sending or receiving.
Hope this helps..