One can use the resource-setting capability of the X-Windows system to set attribute colors. This applies when running under the X-Windows system, which is presently true for all releases except those for Microsoft Windows. However, this is archaic and not really recommended.
One can create an X resource file for Xic. This is a file that should be created in the user's home directory, with a name that is the executable program name with the first letter capitalized, i.e., Xic. The file contains lines in the following form:
xic.HighlightingColor: green
xic.MarkerColor: blue
or generally
xic.resourcename: colorspec
The resourcename is a keyword from the list of attribute colors as listed in A.8.3. Note that the keyword must be used, not an alias. The aliases are recognized in the technology file and !setcolor command. The colorspec string is the name of a color or an RGB triple: