Well 2 things. To answer the actual question of the thread, no you can't just make a manual switch. If you make the manual switch and hook it up to existing 901 batteries they still will not turn on without vacuum(you inhaling). So you'd need to get a manual switch and a regular battery. If this is ok with you, check out the tips and tricks section for something like the magnum. You can build your own manual switch for nearly no money.
Now people may hate me, but I think Taelon may be partly on to something. His high intelligence is making it hard for him to explain. If I understand the dynamics he is talking about, it's not that it "instantly" makes it hotter right off the bat, but you can keep it on longer allowing it to be hotter. In an automatic battery, there "may be" and he said he is not sure, but there may be a thermal switch that regualtes the voltage depending on heat. This way allowing the E-cig to operate at a warm level, not burning. There are 2 potential problems to the manual switch. First being that there is no auto shutoff. This means that you can smoke longer, but the atomizer is getting to dangerous levels if you are holding switch for too long. That is why autos have an auto shutoff and some of the new Ecigs shut off even quicker. The 2nd potential problem is its heating up the stuff on the atomizer THEN you inhale what is already "heated or possibly burnt". Whereas automatic you are inhaling whatever is on the atomizer while it starts to heat, hopefully not leaving time for it to burn.
These are just my possible thoughts. Not sure if they are "scientific" or not, but I think further thought into this might not be such a horrible idea.
Now with that said, I myself prefer my manual switch on the 801 pen style. Never said I care abotu safety...I come from Cigarettes right?
before cooking through the full thickness of the egg film on the pan (this example should make it clear for the nice Americans here, too 
) same for the liquid film on the atomizers heater and in the heaters swam.
