help with secure internet sharing

ok so im tethering my internet off my blackberry to my mac and then sharing it with others (PC's), how would i go about securing the network so others cant just use it who i don't want to ??

ive already tried using a 40bit WEP but the PC's wont connect to the network ?
what can i do to make my shared internet secure and able to be used by PC's?


any help would be appreciated
Ollie

With an ad-hoc network (computer to computer) the only thing you can do is WEP - and it isn't much for security anyway. So if WEP isn't working then you really don't have anything.

You could try to get a broadband router - if you have a compatible blackberry - this is how I do it. You can then enable WPA2. I use cradlepoint.
Extending and Protecting 3G/4G Networks Wirelessly | Cradlepoint Technology