If, and sometimes there s no other way, If I have to use older textures (pré-PP2012) I put a HSV node between the texture and the diffise_color and work with that HSV node to change the texture as needed.

When using this technique, of planes , squares with ambient, you might ad a "pose light to your scene to see what you are doing.

To create a Pose-light?

Add a point light.
Position the light.
Parent it to the main camera with inherit bends ON.
Remove shadows (remove the "V" in the properties palette.)

Goto the mat room and set diffuse and specular to pure black.

You now have a point light that allways shines on your scene from your camera's position, but does not render or make false shadows.

Ideal to work in low light situations where most of the light is coming from IDL.

Happy Posering
Tony

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!