If your definition of "relatively easy" is "something that can take a long time and be annoying", then yes :P
Seriously though, it all just depends on exactly what you are trying to do. Adding 1 door isn't bad. Adding a full zone worth of doors can be quite a pain. The rough part is that you have to zone out and back in to reset the zone each time you want to see the results of your door changes. The other semi-complex part figuring out which door models are available in that particular zone.
The best way I have found to find the names of doors available to a zone is to use S3DSpy (from GeorgeS' site) and look at the zone file in your EQ directory. Most doors will have the word "DOOR" in them, so it isn't hard to tell which ones are in there. But, to see what each one looks like, you would have to try each one out in-game. It can take a while lol.
I would recommend looking at the doors table and getting familiar with it. Then, check the wiki page here for more details on that table:
http://www.eqemulator.net/wiki/wikka...uDBSchemadoors