For who can't host, you can host in wormnet2 if you used Hamachi. But, only the group of who will follow the next steps will be able to host or join the host.

1. install this version of Hamachi:
http://www.filehippo.com/download_hamachi/2101/
I didn't test using other versions.
Note: Hamachi version must be same for all of your players group.

2. click the second button in the bottom. click "Join an existing network ..".
copy then past these:

name:wormNet2
password:123

If this network is full then create a new one and post it here or give the its name and password to your friends. Just click the second button. Then, click "Create a new network ..". Then write a name and password. They are case sensitive and you should write it in notepad before you copy them to Hamachi.

3. Turn off the firewall. And ping each others. Who can't be pinged will not be able to host or join the host.

4. You will see your IP over Hamachi network in the top of Hamachi window.
download the registry file from this post (wwp network config.zip). Then, open it using notepad or "right click" on the reg file and click edit. Replace the ip that exist in the file with your ip. Then save the file and run it.

5. Chat in Hamachi and tell each others who will host.

6. Open wwp and play online!

Note: Maybe you will need to use the same type of OS! Or the newer versions will be able to host.