I have just done this successfully and am connected with it right now.
The easy way is to buy launch2net which is super easy to use. I just installed it, ran it (at which point it auto-configured with no input from me) and clicked "Connect" and it worked. Unfortunately there is a very big drawback to this - it costs an eye-watering €75.
The alternative is to follow the instructions on the Novatel site here
http://www.novatelwireless.com/support/Mac...rd-Apple_3G.htm.
I am on T-Mobile so my settings are:
APN: general-t-mobile.uk
User: <blank>
Pass: <blank>
CID: 1
I tried this several times without success but it works now and I don't know what I did differently except perhaps that the last time I edited the Default configuration for the Novatel modem rather than creating a new one.
Good luck if you haven't already figured it out yourself.