Short answer, you can't.
The reg number can be changed in the Select-a-Plane GUI, or the aircraft.cfg.
You can tweak it a little in the aircraft.cfg in terms of appearance. The position is fixed however.
In the library at Avsim is a file by David Robinson titled regcolor1.zip that will show you how to set a custom color for the reg number. I don't know if it's in this library.
You have a little leeway in terms of size and you can change the font.
For instructions on how to do that get the aircraft container SDK here-
http://support.microsoft.com/kb/555857This will take you to a list of links that will download an .exe file from Microsoft. The site can be trusted.
Happy tweaking!
cheers,
Joe
Answer short and sweet...

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Ta for the reply, Joe...

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I suppose this applies to any Aircraft when the designer only supplies textures showing one side only...

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I could apply the Registration letters to the texture as normal, but turning the aircraft around obviously shows the letters reversed..

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I usually select my Registration letters in the "Select a Plane" option, as you mentioned, but of course, the letters appear in a small MS Font, where I can select the colour, re your other comment...

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Funnily enuf....the main reason why I purchased FS Repaint was to get rid of the zillions of "N" registrations on my favourite Aircraft, and replace them with our happy-go-lucky, British; "G" registrations!....

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...makes me feel "more at home"...

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Cheers Joe.... [smiley=thumbsup.gif]...!
Paul..."G/Gee!...that's a nice registration you've got there"....

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When Uncle Bills mates designed the Default Aircraft they could only find an; "N" Stencil...

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