About 1 year ago I was having trouble to have Huawei E1550 USB Stick working on Mac OS X Lion. A couple of days I have upgraded to Max OS X Mountain Lion and even using Migration Assistant this configuration was lost from my laptop.
Anyway I have found that you can still use the same drivers to make it work with Mountain Lion, in fact I just did it because I needed the stick to work. If you are having trouble please grab the drivers and follow the instructions here.
If you have any tips that might help others please leave a comment on this post and I will update it as it seems there are quite a lot of people looking for this out there.