Since Update June 2015, it's possible to control the reflection of modded items.
Reflection textures can't have their blendmodes changed, blending is configured to be additive - this makes it possible, with a little trick, to actually remove reflections from dress items.

Adding reflection requires an additional texture to be added to the mod.
There's a simple naming convention to follow: Just add a texture with the modded texture name and add .refl to the filename:
E.g. to add reflection to the fetish skirt F_Fetish001_Skirt.png just add a second texture named F_Fetish001_Skirt.refl.png. This texture will then be used as the reflection texture.

This is the one used throughout the games.

To remove a reflection, we're taking advantage of the additive blend mode of reflection textures.
By actually adding a reflection texture, we can remove the reflection effect: just use a simple 1×1 black pixel image as a reflection and the effect is not visible anymore.

It's just scaled up to be displayed correctly here, but the real size is 1×1