3g dongle not working on el capitan
Following are the steps


Restart Machine and press CommandR while booting
It will take you to the Recovery Mode
From Utilities Menu open Terminal
In the Terminal Window enter csrutil disable
Then restart
Install regular EVO drivers that came with the dongle, you will be able to see the modem in Network Preferences and might have to do configuration manually like entering *99# as number etc.
Then restart in same mode as step 1
Open Terminal and enter csrutil enable


It will start working at step 6