No, that's not done with splitters, nor will it work with 2 monitors.

It's done through
Nvidia's Surround setting, which also requires a compatible card with 3 outputs or an SLI setup. (In my case, a single GTX660 which has 4 outputs and is powerfull enough to pull it off).
When I switch to Surround, my desktop resolution switches to 5760x1080 and that resolution becomes available in games as well.
Not all games support it though. By default, ESO doesn't and the interface is spread out across the 3 monitors. (Character screen and chat on the left monitor, inventory and system messages on the right monitor.) Off course, ESO does support mods, and there are mods that add support for Surround (and Eyefinity, ATI's counterpart) and allow for UI customisation.
Most other games that lack native support also have tweaks or mods for them.