If there is an update, they will push it over the air to your phone amd you should get a notification on the notification bar, or at least a notification when you click "software update" on your phone.
The update will come from Virgin, not the LG site.
The update on the LG site is not something you want or need, and I do not know of anyone who has sucessfully installed it, though several have tried, just to see what it was. One contacted LG and they didn't seem to even know it was there.
As far as I know, the only difference between 2.2.1 and 2.2.2 is that the hotspot has been disabled.