if you're going to go to the trouble of making your own part, I recommend using the copy and paste function, and making several diagrams for the same part.
for example, some pics have lots of multiplexed functions on each pin. instead of trying to type all those functions in on a single diagram, and ending up with a huge box full of abbreviations, it's better to break it down like 18f4550 analog, 18f4550 usb + spp, and so on ... then you don't have all the clutter of those functions which have no bearing on your application