In max it's very easy to do with a pelt map, though this was not available 8 years ago.
Looking at the original UV maps, it looks like they were created by max's auto generated cylinder maps. They could have made a seamless UV map, but without the current tools we have today, that would have taken a long time.
i am just using blender . most are just simple unwraps then applying the limit stretch function . some are more complex and require seam marking , simple unwraps , aligning the uv vertices to the edge of the texture then applying the limit stretch function . i use some more complicated methods on things like the stalactites . a few do have seams that can't be avoided so i use vertex shading to hide the seams as best as possible .
i think they did have the tools needed 8 years ago . all of the bitter coast rocks are already seamless (but could use limit stretch done on them) and 95% or so have vertex shading done that could have been used to hide seams as well .
last night i did 44 meshes
x/terrain_lava_pot
x/terrain_lavapot_01 - was already seamless
x/terrain_lavapot_02
x/terrain_lavapot_03
x/terrain_MA_20 , 30 , 60
x/terrain_MA_rock13 , 22 , 32 , 62
x/terrain_MA_rock_13 , 51 , 53
x/terrain_volcano
i/in_bonecave_stal00 , 10 , 20 , 30 , 40 , 50
i/in_lavacave_stal00 , 10 , 20 , 30 , 40 , 50
i/in_moldcave_stal00 , 10 , 20 , 30 , 40 , 50
i/in_mudcave_stal00 , 10 , 20 , 30 , 40 , 50
i/in_pycave_stal00 , 10 , 20 , 30 , 40 , 50
going to search thu files and the cs to see what else needs done to finish the mainland up
-Nich