To set FPS, open ePSXe, click on config, click on video, then click config under the plugin you are using. This should open up a screen w/all sorts of options and among them, will be, the FPS options you are looking for. Set these, close the config screen, exit ePSXe, restart ePSXe and your game and you should be all set.
Hope this helps some.
sincerely,
sx/amiga