As obm890 points out, the UVs are part of the geometry. So in order to swap the UVs, you need to swap (or "switch") the geometry. The attached file is a working example of text of a pp2 that can switch between three geometries (one being the default) via a geomChan (dial name "AltGeom").

There are two parts to geom switching, a list of the alternate geometries including thir paths, and a 'geomChan' channel to do the actual switching. The text below is a snippet from the attached file, and shows the relevant code in green and orange. The orange bits are variable, meaning you can edit them to suit your own purposes.

prop box_1
    {
    name    box_1
    on
    bend 1
    dynamicsLock        1
    hidden        0
    addToMenu    1
    includeInDepthCue        1
    parent UNIVERSE

    alternateGeom    Geom_1
        {
        name Geom_1
        objFile 1001 :Runtime:Geometries:props:ball.obj
        }

    alternateGeom    Geom_2
        {
        name Geom_2
        objFile 1002 :Runtime:Geometries:props:cone.obj
        }

    channels
        {
        geomChan AltGeom
            {
            uniqueInterp
            name AltGeom
            initValue 0
            hidden 0
            forceLimits 1
            min 0
            max 2
            trackingScale 0.045
            keys
                {
                static  0
                k  0  0
                }
            interpStyleLocked 1
            }