If you want a separate power button it could be easily manufactured.
Look at the images 28 up to 31. This is the PCB where the power button is installed. Just solder two additional wires to an electronic switch placed wherever you want. If you want something more flexible you could solder the two wires(coming form the Acer's power button) to a FEMALE audio jack. Either build it inside the tablet or fix it on the side(outside of course - the two wires should have some kind of pass-through the plastic - small hole maybe). Than solder another MALE audio jack to the wires coming from the external button of your choice. Finally when you connect the male-->female audio jacks you are going to have an external button. If you are not experienced enough or have no such soldering iron I highly recommend giving it to a professional. Take the PCB only because the guy would not need the other part of the tablet and it will be cheaper because you won't be charged for disassemble - assemble process.
If you need some more help please ask
P.S. Video of something VERY similar: http://www.youtube.com/watch?v=i7KQeHhgaOY
Nicely explained laptop(tablet...laptop...fridge...or even space shuttle it is all the same: momentary switch
) thread : http://www.mp3car.com/how-to-power-a...er-switch.html
If you are thinking now...what button I could choose and where to find it....I would suggest to just buy an OEM button of some option that is missing in your car. Most of the buttons are momentary buttons which send signal to a controlling module. A typical example : http://acimg.auctivacommerce.com/img...mg/4264076.jpg