Save the model to the Prop section of the Poser library. The path to the texture map will get saved within the Poser prop file. Depending on your version of Poser the file path will get saved either as an absolute or relative path. If using a later version of Poser, and if your texture is within the texture folder it will most likely be a relative path. You can open the prop file in a text editor to check.

Providing it is a relative path the prop can be installed to any correctly structured Poser library and Poser will be able to find it when the prop is loaded into the scene.

Suggest downloading any free Poser prop and see how that has been put together.