According to http://oss.sgi.com/projects/ogl-sample/registry/EXT/paletted_texture.txt, if GL_EXT_paletted_texture is supported then function glColorSubTableEXT should be available.
This function is not defined in javax.media.opengl.GL, only glColorSubTable which isn’t available e.g. in Microsoft’s OpenGL driver. Any comments?
All extension routines which were folded into OpenGL versions 1.1, 1.2, and 1.3 were removed from JOGL’s GL class a long time ago in the JSR-231 standardization process to reduce the number of duplicated functions. Sorry, but this means that this routine isn’t available if you’re running on a pre-OpenGL 1.2 implementation.
From what I’ve heard paletted textures are implemented horribly inefficiently on modern cards due to the move away from indexed color schemes so my recommendation would be to try to find a different solution using shaders for current OpenGL implementations and recompute and re-upload the texture bits if you have to run on OpenGL 1.1.