Fading between textures.

[BlueMustache]

Hello Community,
I am making some scripted keypads in gmod that look nice, and I was wondering this.
How do I (assuming the background of this keypad is render to texture) switch from the texture being A to texture B in a smooth fade effect.

[IMG]http://i.imgur.com/UMjhyQr.png[/IMG]

I will have the two textures seperated, but how to I fade between textureA.vtf to textureB.vtf?
And while I'm at it, how would I then take that and overlay an animated vtf. Such as rolling scanlines making the keypad look better.

Sorry if TL;DR (I suck at that. D:)

Thanks.

[BFG9000]

Draw one on top of the other and fade the alpha over time?