The specific steps involved in replacing a 6.0 high Pressure Oil Pump depends on your model of vehicle but some standard procedures are applicable for most tasks involving removal and replacement.
Initially you'll need to remove any parts that obstruct your ability to reach the pump. On some models this could mean removing the intake, but this can be done on some models. You will likely need to remove exhaust, turbo, and alternator for access. You won't need to disconnect the battery or drain any fluids.
The first steps involve removal of the old pump. First drain the oil from the old pump by removing the end plug from the attached port. You will need a container to collect the oil in. Once you remove the old port and o-ring then remove both high pressure oil hoses that are attached to the old pump. Then use needle nose pliers to remove the spring and check assemblies from the old pump.
When you need to remove or install the discharge fittings be sure the thickest part of the springs in the poppet are facing outward. The springs will be placed inside the main housing for the oil pump with the fittings going around them on the outside.
Next you can use any available brake cleaning product to wash both fittings and end plug ports. Once both ports in the pump housing are clean and dry as well apply Loctite 680 sealant to the first three threads on the discharge fittings and the end plug. Then install both high pressure hose fittings and the plug, remembering to wipe oil from the port immediately after installing the plug. Torque to 34 Nm(25lbf ft) Then start the engine and check for oil leaks, checking and correcting the oil level as necessary.