To edit the Building Textures, you simply need any image editor that can work with 256 color bmp with palette. Extract the bl320-?.dat with the pal0-?.dat palette with Ted’s Raw Editor and start editing, but make sure that the textures are the correct size and put to the correct position. The first color used in the palette will represent the Transparent and it will be the transparent color in game.
The original Building Texture files are same for all Terrain Styles. If you’re going to use the file within all styles of your mod you should only use the last 128 colors to ensure that they’ll look correct on all styles. If you take a look at the Prison there are some bad pixels because of the original file didn’t followed this. However if you’re going to add special things that’s only applicable for a single style only you’re free to use the entire palette.

2 Selection
3 Selection
4 Selection
5 Selection
6 Selection
7 Selection
8 Selection
9 Unknown
10 Selection
11 Selection
12 Tree
13 Unknown
14 Unknown
15 Unknown
16 Selection
17 Blue Hut
18 Red Hut
19 Yellow Hut
20 Green Hut
21 Unknown
22 Unknown
23 Unknown
24 Selection
25 Blue Roof
26 Red Roof
27 Yellow Roof
28 Green Roof
29 Hut Side
30 Hut Side
31 Unknown
32 Selection
33 Blue Warrior Hut
34 Red Warrior Hut
35 Yellow Warrior Hut
36 Green Warrior Hut
37 Building Addon
38 Building Addon
39 Building Addon
40 Building Addon
41 Blue Firewarrior Hut
42 Red Firewarrior Hut
43 Yellow Firewarrior Hut
44 Green Firewarrior Hut
45 Blue Temple
46 Red Temple
47 Yellow Temple
48 Green Temple
49 Hut Plan
50 Hut Plan
51 Hut Plan
52 Hut Plan
53 Hut Plan
54 Hut Plan
55 Hut Plan
56 Hut Plan
57 Blue Spy Hut
58 Red Spy Hut
59 Yellow Spy Hut
60 Green Spy Hut
61 Unknown
62 Unknown
63 Unknown
64 Hut Plan
65 Software Render Red Hut Plan
66 Software Render Red Hut Plan
67 Software Render Red Hut Plan
68 Software Render Red Hut Plan
69 Software Render Red Hut Plan
70 Software Render Red Hut Plan
71 Software Render Red Hut Plan
72 Software Render Red Hut Plan
73 Fire
74 Fire
75 Fire
76 Fire
77 Fire
78 Unknown
79 Unknown
80 Software Render Red Hut Plan
81 Fire
82 Fire
83 Fire
84 Fire
85 Building Addon
86 Building Addon
87 Building Addon
88 Building Addon
89 Fire
90 Fire
91 Fire
92 Fire
93 Fire
94 Fire
95 Fire
96 Fire
97 Fire
98 Fire
99 Fire
100 Fire
101 Fire
102 Fire
103 Fire
104 Fire
105 Blue Boat Hut
106 Red Boat hut
107 Yellow Boat Hut
108 Green Boat Hut
109 Fire
110 Unknown
111 Unknown
112 Unknown
113 Blue Balloon Hut
114 Red Balloon Hut
115 Yellow Balloon Hut
116 Green Balloon Hut
117 Firewarrior Hut Side
118 Firewarrior Hut Side
119 Stone Head
120 Stone Head
121 Temple Side
122 Temple Side
123 Temple Side
124 Temple Side
125 Stone Head
126 Stone Head
127 Unknown
128 Unknown
129 Unknown
130 Tree
131 Unknown
132 Unknown
133 Unknown
134 Unknown
135 Unknown
136 Unknown
137 Tree
138 Tree
139 Tree
140 Unknown
141 Unknown
142 Building Side
143 Building Side
144 Building Side
145 Vault of Knowledge
146 Vault of Knowledge
147 Unknown
148 Unknown
149 Unknown
150 Unknown
151 Building Side
152 Building Side
153 Building Side
154 Building Side
155 Blue Tower
156 Red Tower
157 Yellow Tower
158 Green Tower
159 Totem
160 Totem
171 Prison
172 Unknown
173 Blue Angel of Death
174 Red Angel of Death
175 Yellow Angel of Death
176 Green Angel of Death
177 Unknown
178 Totem
179 Unknown
180 Unknown
181 Blue Angel of Death
182 Red Angel of Death
183 Yellow Angel of Death
184 Green Angel of Death
185 Unknown
186 Unknown
187 Unknown
188 Prison
189 Prison
190 Vault of Knowledge
191 Vault of Knowledge
192 Vault of Knowledge
193 Vault of Knowledge
194 Vault of Knowledge
195 Vault of Knowledge
196 Vault of Knowledge
197 Blue Tower inner and Boat
198 Red Tower inner and Boat
199 Yellow Tower inner and Boat
200 Green Tower inner and Boat
201 Unknown
202 Unknown
203 Unknown
204 Neutral RS Pillar Texture
205 Blue RS Pillar Texture
206 Red RS Pillar Texture
207 Yellow RS Pillar Texture
208 Green RS Pillar Texture
209 Unknown
210 Unknown
211 Unknown
212 Neutral Balloon Texture
213 Blue Balloon Texture
214 Red Balloon Texture
215 Yellow Balloon Texture
216 Green Balloon Texture
217 Tree
218 Tree
219 Stone Head
220 Neutral Balloon Texture
221 Blue Balloon Texture
222 Red Balloon Texture
223 Yellow Balloon Texture
224 Green Balloon Texture
225 Building Side
226 Building Side
227 Building Side
228 Building Side
229 Vault of Knowledge
230 Vault of Knowledge
231 Vault of Knowledge
232 Vault of Knowledge
233 Building Side
234 Building Side
235 Building Side
236 Neutral Roof
237 Blue Roof
238 Red Roof
239 Yellow Roof
240 Green Roof
241 Tree
242 Tree
243 Selection Light
244 Selection Light
245 Selection Light
246 Selection Light
247 Selection Light
248 Selection Light
249 Selection Light
250 Selection Light
251 Unknown
252 Unknown
253 Arrow of Hut Plan
254 Unknown
255 Unknown
256 Unknown
257 Unknown
258 Unknown
259 Unknown
260 Unknown
261 Unknown
262 Unknown
263 Unknown
264 Unknown
265 Unknown
266 Unknown