From what I can gather, and I'll edit once I know for sure so that google will pick it up in the future.
1 You have to have a snapshot image for your planet, even if you delete all but one object. (this is what I did). /snapshot/taanab.iff
1a. Take the Yavin4 snapshot, browse through the nodes until you find outpost_starport something... there will be two (maybe three but I didn't bother with the imperial one).
1b. You want to keep those two nodes AND their child folders. Everything else can be deleted with ctrl+del. just hold the button down and let it rip.
1c. You will need to set their x y z locations BUT you really can't do that until you get zoned into the planet and find some flat space to work with.
2 Even though there's a taanab.iff environment file (in datatables/environment) in a .tre file, it doesn't work. you have to make your own. again you just need one environment group to work, but the one in the .tre doesn't work.
2a. this seems to be a bit fickle. the first time it didn't work, but the 2nd time it did. I'm thinking that some .tga or .dds files were missing on my first attempt but are working fine on the 2nd. either way you need one group of 5 rows for each weather stage. Look at the other environment files to get the feel for a new one. Or TRY the taanab file and if you get that magenta sky then try copying another environment file instead.
3 it appears that you need a client region as well /datatables/clientregion/taanab.iff. Just copy an existing and remove all but one region. I copied lok.
3.a the clientregion file basically sets up your no-build npc_city regions. take an existing, copy it, and change it however you like.
3.b once you've zoned into your world you can find nice flat space and save those coords. go back to your clientregion file and use those coords as your new NPC city area's.
4 make sure you put the files in the same file structure that exists in the .tre files on both the client & server (although the server might not need them all)
5 server side you need to edit your planet_manager.lua to include a section for taanab, even if there's nothing in it. There's also some LUA files you can change to allow for player structures and the like.
5.a make sure to add "taanab" to your city_manager.lua file so you an build cities there.
5.b in your bin/scripts/objects folder locate your structure deeds and make sure you add "taanab" to all the ones you want to be placed there. teadious work but if you want a house on taanab you have to edit the deed script.
6 make sure you remove the -- from taanab in the config.lua file
couple of new notes. This is still a trial and error process for me and I've done it three times in total now. a real PITA. You really need flat land to add things like starports and structures. the best place for these is in the snapshot file, but you CAN add some through the planet_manager.lua file. However, some items you might try to add through the planet manager script will crash the client. trial and error will get you some nice decor but it's limited.
the travel system isn't as intuitive as I would like, but it's also REALLY simple. first the planet_manager.lua file just lists destinations and weather they accept incoming and/or interplanetary travel. this just sets the available landing points and where to zone your character into. in your .tre files there's a travel.iff file that's a grid that's easily editable. it gives you your fairs and what planets can be traveled to. 0 = no travel, > 0 gives you your fair to that point. In order to add taanab you have to add a column for taanab (or another planet name) and set it's fairs. But tre-explorer doesn't allow you to add a column that I could find. I had to HEX edit another table iff with the correct number of columns and hack it in. took a while but I finally figured out what most of the bits meant and was able to properly size & edit the file from HEX. then I opened it up in tre-explorer and added the $$ values to the file. Again, if there's another, better way, to add a column to an IFF file then fantastic use that. I couldn't find a way so I took another datatable with 14 columns and hacked it in a HEX editor to suit my needs. Lastly you need a travel terminal and a ticket collector. these can be added through the planet_manager.lua file. They just work by default as long as your IFF & LUA files are correct.
One more new thing that got left out. You need your new planet to have a valid CRC so the client and core can do things like add waypoints, do missions, quests, etc... you can do this by editing the /misc/planet_crc_string_table.iff file. There's a neet little CRCTool on modsource.com if you fish around. using the tool you simply add a new CRC string to the file, repack your .tre file and you're good to go.
Editing the Client Travel and planetary GUI are more involved and won't make it into this post as such. I still need to -redo- my work to make sure even I understand what I did before I post a guide on it.
-Duff