well the theory is, manually upshifting an automatic doesn't hurt it anymore than letting the computer do it for you. Well it may cause a tad more wear than normal daily driving. The only thing this will benefit you is being able to control the shift point, letting your engine rev higher. But downshifting is a nono, this will cause even more wear upon the tranny. Depending on where your downshifting too can be a great deal. For example: D4 to D3 is ok, but D4 all the way down to 2 or 1 is just stupid.

Not all Honda transmissions are bulletproof whether new or old you can surely beat the crap out of them more than you can our american counterparts. There will be a time where that tranny will go out... just don't make that time any sooner than it must be.

If you really wanna shift, do a 5spd swap, or buy a car with 5 or 6spd....it is so much better.