First off, shifting an auto MANUALLY is retarded. You won't go faster. Also, shifting manually can cause wear on the shift linkage, and on the trans itself. Shifting and hitting the gas is the worst, since it causes the trans to not shift correctly.
Brake torqueing is virtually harmless in the fact that the transmission's stall RPM is used normally while driving, brake torqueing merely takes the engine to the stall RPM and when you release the brakes you have the power there rather than if you just step on the gas. It's marginally faster.
Ohh yeah, and don't go flat out in first up to the redline, let off, and slam on the gas again. While you could get a 2nd gear skid, you're completely stressing your transmission. I've done it, by accident(getting onto the highway, I went flat out in first then had to swerve to avoid road debris so I let off for a split second and hit the gas again and "BANG". Not good!
Some transmissions have delayed shifts from 1 to 2, since you're driving it like a moron. Again, if you want manual shifting you're gonna have to go to a junkyard and find a 5 speed Maxima and swap it over. It can be done.