Does a ITS box need full hydraulic steering to work, or will it plumb into the brazil valve. There are only two steering lines coming out of the box.

The ITS needs full hydraulic steering. There isn'a a "tiller arm" to attach the cable/valve/cylinder to. The 2 lines connect to Merc's connector block which includes cross-port relief valves, bleeder fittings, and also has a removable secondary block that the standard Bravo style pump/cooler-return lines can be connected to from the engine.

Where can i find a diagram to run the lines?

It's in the installation manual, I will see if I can find it and send it to you. What type of install? Single, Dual w/single pump, Dual w/twin pump?

I have a single engine with no steering, going to ITS with full helm. Thanks for your help

I have attached a scanned image from the manual of the single installation. The ITS is really the same as other full hydraulic setups except Merc allows the use of the standard pump/cooler connection lines normally used on with the cable system. They also include the bleeder fittings and cross-port relief valves for the R & L lines connections in the connection block.