For the Main Text Box in the (default) top-left hand corner you can set the text to have either 6 colours. 

c0 = Dark Blue 
c1 = Dark Green 
c2 = Light Brown 
c3 = Light Green 
c4 = Light Blue 
c5 = Dark Brown 

Ex: 
messageClient(%col.client, 'Msg', 'c2This text is Light Brown'); 

To set the colour in a print statement use the following. 

<color:000000> = Tribes Blue 
<color:7c7c7c> = Grey 
<color:FFFFFF> = White 
<color:FF0000> = Light Red 
<color:7D0000> = Dark Red 
<color:FFAE01> = Yellow-Orange 
<color:FFF601> = Light Yellow 
<color:1FFF01> = Light Green 
<color:199500> = Dark Green 
<color:0EE3CC> = Light Blue 
<color:0EAEE3> = Medium Blue 
<color:001EFF> = Dark Blue 
<color:C600FF> = Dark Purple 
<color:FF00F6> = Light Purple 
<color:FF008A> = Pink 
<color:8BBD03> = Grass Green 
<color:085900> = Super Dark Green 
<color:FFE505> = Dark Yellow 
<color:BAA707> = Yellow-Brown 
<color:BA7007> = Light Brown 
<color:BA3E07> = Dark Brown 
<color:F3F56C> = Beigh 
<color:FF6600> = Orange 

Ex: 
bottomPrint(%obj.client, "<color:FFFFFF>This is the colour (shade) white., 5, 1);