Guide wise, no, always been meaning to, but been too busy with other stuff.
SIE really makes it a cakewalk though, it hands one everything on a silver platter, especially with my templates.
You can extract with SIE, you can also extract with TreExplorer, so not sure why you seem to not be able to. You only need to pack .tre's if you're doing any server related stuff. Sytner or I will most likely add a simple .tre packer soon, but for now, you can simply use this one:
http://www.modthegalaxy.com/forums/thread-tool-tre-packer
So, taking all that into account, grab SIE, extract/manipulate the files you want, then for client side stuff you can simply put them in your SWG directory with the correct folder structure (texture/example.dds inside a .tre would then go to your swgdirectory/texture/example.dds), or for server related things, pack a directory (that contains the proper sub folder structure, as with the client side example) and slap it into your server/client. Though, for server stuff, I can't really help, but Lasko has written some nicely done guides or step by steps on how to add stuff like the BARC, which can be found here:
http://www.modthegalaxy.com/forums/thread-adding-the-barc-to-the-emu-core3
I noticed that Lasko used a different tool to pack, he also used TreExplorer, which he shouldn't, since SIE is out now.
P.S. Moved it to Server Content Discussion, because I have a feeling you're trying to do server related stuff, if that isn't the case, let me know, but Guides is only for actual guides.