Peter,
might it work if you respond to the person at Sony who stated that you were trying to modify their product, and explain that you are not trying to modify the product, but you are trying to verify whether its existing remote control codes can make it qualify to be a product recommended nationwide to installers and programmers. This recommendation would be based on the existence of discrete codes, if they exist.

AND that cooperation in this matter is bound to increase sales, which you understand is actually a corporate goal (that they are standing in the way of); lack of cooperation in this matter is bound to result in system integrators and installers nationwide avoiding the use of this product. (I think "boycott" suggests that you want a confrontation or suggests that you are exaggerating.)

I have asked friends at Xantech about this whole topic, and they find the manufacturers to be uninterested in helping out xantech or us.

Ernie