Alternative to paletted textures

I currently use paletted textures (through glColorTable() extension) in my volume rendering application (http://members.tripod.com/~clunis_immensus/free3d/).
I use it not for the compression, but for the ability to vary the look-up-table for 2d & 3D RGBA textures at interactive rates.
Is there any other efficient way of updating the texure LUT ?
I ask, as only Nvidia and 3dlabs seem to support paletted textures and the palette resolution is limited to 8-bits.

many thanks!
Karthik

Use dependant texture reads (GF3 and up, look for “GL_NV_texture_shader”; Radeon 8500 and up “GL_ATI_fragment_shader”; or even “GL_ARB_fragment_program”).

Maybe you can even do this with EMBM (Radeon 1 and up, “GL_ATI_envmap_bumpmap”), but it may not be as straightforward as you want it to be.