Preface: I read your post in that other thread as well.
My question is, why do you want to do this? It can be done, but for the money you'll invest (especially if you pay a shop to do it) I think the performance gains will be very negligible. If you can't or won't convert to manual, then I think you'd be much better served by adding forced induction to your current engine.
Yes an LS or B20 engine will give you a few extra horses and a little bit of extra torque, but really it's not enough to make a huge difference. And, please realize that the reason a B16 or B18C (the VTEC models) are more fun ALSO has to do with the transmission, especially in the B16. The gearing on those cars is shorter, therefore you get to the higher RPMs quicker and stay there when you shift.
You could eventually build yourself an LS or B20 VTEC, but you wouldn't be getting the full potential out of it if you're stuck with an automatic LS transmission and it's longer, economy-minded gears.
Do you know anyone who has a fairly stock automatic Integra that they'd be willing to let you drive? If so, do that before you make any decisions. I mean, who knows? You might just be impressed enough with it to make you want to invest the money to install an automatic LS or B20 in your car, but honestly I'd put money on you being disappointed with it.
A turbo setup however, would provide you with a good amount of additional, useable torque. The car would actually feel significantly faster...
