ok first off you want to get DXTBMP here on SimV. It will be in the utillities section.

In the aircraft folder there will be a subfolder named,"Texture" Get thew appropriate file for the livery.

You can use DXTBMP to change the encoded pic into a normal image.

Then take that image and put it in MSpaint or some other program like that.

Repaint over the nose white.

recode file using DXTBMP.

Make a backup of the opriginal texture file.

Replace the old one, and your good to go