If your processor only has one PHY, you're not going to get a lot more speed by embedding the switch on your board. It will be much easier to just add a switch:
As the text on this example indicates, any halfway decent switch will autonegotiate 10/100/1000 Mbps, cable crossover.
Switches are available in anywhere from 4 to 48 ports, with 5 ports being a common number for simple desktop switches. They can sit on your desk or be rack-mounted. You can chain them together for ridiculous numbers of ports, if you feel so compelled. You can get them for less than $10 (visit Newegg), or as much as 10,000. One important thing to consider is whether you want a managed or unmanaged switch, but we'd need more information to make this decision, and this is swiftly turning into a question for ServerFault.
An external switch is probably the most flexible, simple, and cheap way to do what you want. It will be physically larger than putting the contents of a switch on your PCB, but I wouldn't do that unless it was absolutely necessary.