Using a RealTek Ethernet Switch
The RTL8305SC doesn't require any actual code, but you need to read through it's datasheet for a good description of how to wire it up.

In general, connect the output of the PIC's ethernet to one of the RTL8305's ports in a cross-over (or enable auto crossover on the RTL8305). Connect the rest f the RTL8305's ports to ethernet jacks (w/ magnetics).

While I haven't used this particular switch, it's usually easier if you release the switch from reset, then enable the PIC's ethernet core. But if you do things the other way, it will just look like an unplugged cable to the PIC.