The Cell C black stick is also an E1820 and it plays nice with SL. Tell me, did you install the nonsense that comes with the stick? If so, how are you connecting? I installed Cell C's stuff but seldom use it. After install, Huawei drivers (kexts) should be loaded (you did restart?). Go:
System Preferences -> Network -> HUAWEIMobile-Modem -> Tel no = *99#; Ac name = ""; Password = "anything"
Check the "Show modem status in menu bar" setting.
Now the phone thing is in the menu bar. Click it and the drop-down will have a connect option which works for me.