Bottom line - not too well.
Few 8910 facts:
Special Protocols 1.17 spreadsheet gave me no choice of S3C8+ for 8910/HTPro. So I took what came out anyway.
Upgrade protocol 0 = 01 FC (S3C8)
00 00 01 E4 03 82 50 C0 50 C1 50 C2 50 C3 50 C4
C6 CA 16 7A 70 CB 70 CA 70 C4 70 C3 70 C2 30 C0
End
Both the device and the protocol went to IR, where I defined
1. Macro : 2=ch+;ch+;ch-;ch-.
2. Keymove: VCR/5=TV,<N/A>,TV,1103,$16 where $16 is the 2 key.
Macro on 2 works fine standalone for TV, DVD, RCVR and VCR modes.
Shifted vs unshifted makes no difference (except for that nasty deep-set Set button!)
Issue 1: I can't put macro on phantoms, unlike in 7800 version.
It looks like keys are missing from the dropdown in Special Protocols.
Last key in the list is Swap, $3C. I don't think SP uses RDF.
Issue 2: As a DSM, the keymove does not work even on the above simple test.
> The remote may reset completely especially in VCR mode.
> If not reset, then the LCD looks like reset for a while but recovers to my upgrades (this is similar behavior to the faint blink people report in 7800).
> It might blink once, not run a macro at all - happens more when DVD is active device
I see that the 8910, 7800 and 1994 versions are virtually identical. The same thing works in unextended 7800. Don't know about 15-1994, but I suspect it's ok considering how common this remote is. In case this is relevant - I noticed that PB disassembles the last instruction as JP RRC0. IR sees it as indirect through RC0. What happens at $167A or $7a16? Might that be the cause?