I haven't used Netspend, but its worth giving it a shot if it can be used internationally. Carbon says that the only two requirements for using a prepaid card is that the card should be able to be used internationally and that the card can be used for online purchases. If that is the case your netspend card should work.
Give it a try and let us know how it goes. I have a blog post on how to get money into Carbon accounts for US players and would love to know if Netspend is a successful option. I noticed that depositing into carbon was an issue for people so I made a youtube video with step-by-step instructions on how to deposit with Money Transfer (without paying any fees). In the video I walk you through the process and document myself depositing with this method. You can check it out if you are interested http://youtu.be/Yog5MA7DvHE
Not sure if posting that link is appropriate in this forum because i know the rules say we aren't allowed to advertise our own content but it does answer the question that most US players have about how to get money into Carbon. I'll pull the link out of this post if i am violating any on the forum rules.