Creating PCB footprints is usually quite easy as most components come in standard packages.
Footprints for ‘magjacks’ (RJ45 with built-in Ethernet transformer) are another thing as different manufactures tend to at least put the LED pins at different positions.
Here is an Eagle PCB footprint I created for the MagJack (MJF13T36L-KF06B3GY-0808) from MoreThanAll sold by Sparkfun.
This one has been proven in production and it works, however you should double- (and triple-) check pin-outs and footprint of your device before sending a PCB for manufacturing using this part. Use at your own risk.