cg_fpls 1 works in MP (haven't tested it in SP). The only trouble is that the model's head gets in the way (JK2 used a semi-transparent model in SP and MP.. in fact it was an "arms only" model, though there was also a headless model).
Raven staffers have said time and again that they don't plan to implement this in JA like they did in the previous game, hinting that the feature was just "thrown in at the last minute" in JK2 and "never really supported." To do it in JA would require they "do it justice" by making it fit with every custom model in the game, and since that would be "too much work" they won't do it.
Thankfully OpenJediProject has this included as a "to do" feature if I'm not mistaken, though it may take on a slightly different "trueview" approach rather than a straight port of the JK2 version (though I've been begging RA for the option to use one like JK2 had with the arm's only skin).
g_speed is a server side command that controls game speed. Change it from the default (lower for slower, higher for faster) and you can find something you like.