RS232 and IR are completely separate ways of creating control signals inside of a component to tell it to do something. I think you should go back to that post about the Denon 3805. Rereading it, you'll probably find that those codes are not conversions of RS232 codes, but hidden IR codes or extended IR codes that the unit responds to, but that are not put on the remote for lack of wanting to spend the money to make such a remote for the three guys out here who want to do that.

So what you want to do is start bugging the distributors and manufacturers of the Integra product for all the snazzy IR codes that the really serious installers somehow can get hold of. I say this based on the fact that there are such codes for Yamaha and imagine it might be the same for Denon, especially since you've already seen such codes for the 3805.