theres 2 differant new targets, the first is with weapon safty on (default y), then you can fire at your intended target (default middle mouse button) without the cursor being on them.
the other works almost the same as the other one, except you go into your options, targeting, and map the auto fire key (the key at the bottom of the list).
id recomend mapping it to something easy, then press that and you will auot fire at whatver your intended target is