Your PS3 needs to be set to Linear PCM and NOT bitstream. Your PS3 can decode all advanced lossless compressed audio formats like Dolby True HD, DTS-HD-HR and DTS-HD-Ma into the uncompressed PCM format. This uncompressed Linear PCM format can be carried using HDMI cable to your receiver. Your receiver will detect this format as multi channel PCM. Your receiver will not know what the original lossless compressed format was. All it knows is that it is uncompressed PCM. And there is no difference!
So, just make sure your receiver detects 5.1 or 7.1 PCM and even without applying any processing such as THX audio, Dolby Pro Logic IIx, etc, you should get signal from at least 5.1 if not 7.1 speakers.
And don't worry about the Dolby True HD or DTS-HD-Ma formats showing up on the receiver. As long as the PS3 info shows that it is using the DTS-HD-Ma or Dolby TrueHD, that is all you need to make sure.