I did some more reading here:
Used Moninfo.exe to find the modeline for the SEIKI 39" 4k:
Native/preferred timing.. 3840x2160p at 30Hz (16:9)
Modeline............... "3840x2160" 297.000 3840 4016 4104 4400 2160 2168 2178 2250 +hsync +vsync
Converted that to a DTD:
04 74 00 30 F2 70 5A 80 B0 58 8A 00 00 00 00 00 00 1E
Then I edited the INF file for the driver of latest intel HD driver:
HKR,, TotalDTDCount, %REG_DWORD%, 5
HKR,, DTD_5,%REG_BINARY%, 04,74,00,30,F2,70,5A,80,B0,58,8A,00,00,00,00,00,00,1E,37,01 ;3840x2160@30
installed the new driver, and verified the registry had the correct entires, rebooted, and still no option for that resolution.
I should also note that I CAN use the utility from intel to add a custom res of 2560x1440@30p , no problem there.
You can see below that this resolution does show up in the "list all modes" dialouge and it works when i choose that. If i could figure out where in the registry or elsewhere these list of modes is stored, i venture i could add the 4k mode no problem, so far I haven't been able to find where this info is stored in the registry.