Figured it out, (partly) can export the file to say desktop and use a icon editing program like IcoFX2 to edit file doing the following.

1) select all and cut image out.
2) create new icon and modify to desired image
3) select menu item IMAGE / Create windows Icon From Image.
4) ensure selection of all icon image sizes which you can take from original file.
5) click ok and this will create icon in different sizes creating a strip like original file
6) save as #123.ico or which ever file you wanted to change
7) in customizer god double clikc icon you wish to change to import new file.

this has worked for me, i have changed and create red hud theme styled Network tray icons and modified the volume icons slightly for personal effect. i will show results later when i have done a few more.

I wonder however, if i wanted to put into the install files for red hud (which i have backed up and saved) coud i add these to it to save me time manually updating my own changes if i us theme on another machine?

Also can anyone tell me the difference between hud red top shell and hud red in theme choices? theres a couple and only thing i noticed so far was that with hud red some of the custom sounds were not included and top shell appears to me more complete....