Probably the easiest is to create a color table (.ctbl) file that contains your segment names. The format is a simple text file that you can create in any text editor:
0 background 0 0 0 0
1 first 128 174 128 255
2 second 241 214 145 255
3 and_the_last_one 177 122 101 255
You can use this color table like this:
- Load this color table into Slicer
- Load the labelmap volume into Slicer, in Add data dialog check “Show options” and check “LabelMap” checkbox and select your custom color table
- Convert the loaded labelmap volume to segmentation volume by right-clicking on it in Data module