harrip:
Perhaps you should consider the twin endorsement as part of the 10 hours general handling which is part of the CPL. Instead of wasting 10 hours in the training area, you could use part of those hours towards the endorsement.
Most schools will take some convincing to do it, thats because they wouldn't think of it or they are too set in their ways. At present CASA has upped the hours of the twin endorsement from 5 hours to 7. So what you do, is fly 2 hours in a good twin simulator getting used to the throttle quadrant, power settings and the speed of the aircraft. You can can also practise some of the phase 1 drills in the sim so that you have a better idea of it in the air.Also if you have a good instructor who thinks outside the box he can teach you a lot. You can practise go-arounds etc, discuss assymetric flap problems, runaway props, its really all up to your instructor and how quickly your willing to learn.
You won't have any trouble in the air. A friend of mine did just that and despite all the gurus telling him he would find it difficult, had no problems. It also means you will not have to do a twin endorsement as part of the I/R if its done on a Seminole, Duchess or Twin Comanche all of which are common I/R training aircraft. If you are then told you will be rusty if you havent flown the twin for a while & that you will have to spend time in the training area to get up to speed for the I/R. Thats isn't a problem, because you can do 20 hours sim as part of the I/R and you can use this time to get to learn the procedures and get up to speed in the twin.
Unfortunately in GA the schools do not put to much emphasis on the simulators, but thats because they dont know how to use them to their full benefit.
When you get to do the I/R get your instructor to give you traffic in the sim.
So when your doing an I/R navex, you can get used to managing traffic, ie reducing your speed , talking to the other aircraft all can be practised in the sim. There are some schools who will tell you its better to reduce the sim time and fly because it's more realistic. Thats rubbish, you can save money and get better value if the simulator is utilised properly and you have an experienced instructor who is more interested in training you, then logging twin time.