Well your inc_functions.asp and pop_profile.asp files are probably modified already so I'll just show you the first line of code you need to look for.
in inc_functions.asp
here is the first line of the first section where you'll need to add code for your new smilies (just use what is already there as an example):
fString= replace(fString, "<img src=icon_smile_angry.gif border=0 align=middle>", "[:(!]", 1, -1, 1)
here is the first line of the second section:
fString = replace(fString, "[:(!]", "<img src=icon_smile_angry.gif border=0 align=middle>")
in pop_icon_legend.asp:
Just look at the file and you should be able to figure out what you will need to do (just use the existing code as an example.)