"Zone" for dynamic tail number

[courascrap]

Hi,
In FS2004, does anyone know how to create a "zone" that will hold the tail number that the user will choose?

On all aircrafts coming with the game, you change your tail number and it reflects on the aircraft. I'm using Paint Shop Pro 8 to repaint aircrafts.

I know how to change the color of the tail number but that's all that I know on that registration number.

Thanks,
Nick