Looks like with the new .set files in the theme folder of the 5.3 update, replacing the taskbar icon with a personalized one should be pretty easy ...
BUT I am yet to try it myself, so I'm just assuming ...

EDIT: Scratch that idea ... YES the icon can be changed in the .set files BUT then it behaves just like the cfp.dll file in that the main program requests to be updated due to the altered .set file not being recognized ...