Keez, this is what I found out.
1. Only the Squad CO may upload nose art.
2. After the nose art is created, place it in aceshigh/squads directory.
3. Go to "Club" menu in clipboard, then to "Squad" menu. Upload nose art from there. The text buffer won't inform you anything(no "Nose art uploaded" sort of message)
4. It takes some time for HTC to evaluate your nose art and approve it. Mine took about 3 days. Noseart can be used only after approval in MA and CT.
5. But U may upload nose art instantly in TA.
6. So, if U can't see your nose art, try going to TA and use external view to see if it shows. If it shows in TA as it should, and it doesn't show in CT or MA, it means it is still being evaluated. If U can't see nose art in both MA/CT and TA, it means something is wrong with the nose art.
7. Once nose art is approved, u may change the nose art if you wish, without having to upload nose art again. Thus, delete former BMP file in squads menu and replace it with new BMP file. In my case, I've made 4~5 nose arts and named them Kweassa.BMP, Kweassa1.BMP, Kweassa2.BMP etc etc.. so that I may change it upon occasion. If I want to use a new nose art, I name the new file "Kweassa.BMP" and rename the former nose art file to something else.