The changes for FreeBSD are mainly to do with fonts as some fonts have different names on FreeBSD, to Linux. These might work on Linux as well but I have not tested them. All of what is in here can be put in your $HOME directory and should just work
This is a simple one line script that will change your .Xdefaults file on the fly to edit your XTerm/UXTerm/URXVT color scheme, they are all the same files but with different fonts and colors. use is as follows 'sh .scripts/chc.sh [name of file]' and it should just work, replacing '[name of file]' with the scheme you want.