Could it be the texture count parameter that you are looking for, in the texture generation step? This allows you to split the texture into several maps keeping each one below the maximum dimensions for your card. I haven't checked it in the latest version but think it's only available for generic mapping mode, otherwise perhaps you can modify the uvs yourself in blender, I think you can now import a model with multiple texture maps. I would normally test it myself before suggesting it on here but am out of the office today.