Well it is very simple :)
I will show your a example 
You have to replace the required ranges in for the 4 "ranges"; So this is the info you've sent to me
1 --------> pci 0000:08:00.0: reg 10 32bit mmio: [0xf8000000-0xf8ffffff]
2 --------> pci 0000:08:00.0: reg 14 64bit mmio pref: [0xd0000000-0xdfffffff]
3 --------> pci 0000:08:00.0: reg 1c 64bit mmio: [0xf6000000-0xf7ffffff]
4 --------> pci 0000:08:00.0: reg 30 32bit mmio pref: [0xf5f80000-0xf5ffffff] 
I will do it for the number 1
1) You will have replace the required values in tools/firmware/hvmloader/acpi/dsdt.asl 
    Search for the words  "/* reserve MMIO BARs of gfx for 1:1 mapping */" in the file
    and the first block AFTER  need to be    change like that 
         Here the reference is 
     "pci 0000:08:00.0: reg 10 32bit mmio: [0xf8000000-0xf8ffffff]"
---------------------------------------------------------------------
         "/* reserve MMIO BARs of gfx for 1:1 mapping */
                     DWordMemory(
                         ResourceProducer, PosDecode, MinFixed, MaxFixed,
                         Cacheable, ReadWrite,
                        0x00000000,
                        0xF8000000, // the min value in hexadecimal, I modify it here
                        0xF8FFFFFF, // the max value in hexadecimal I midify it here
                        0x00000000,
                        ???????????) // value = max - min + 1 in hexadecimal value, I need to find it
---------------------------------------------------------------------------
You need to convert the min and the max and do the conversion
For hexadecimal/decimal conversions,  go to a site like 
http://www.statman.info/conversions/hexadecimal.html for doing conversion
For min and max values, you will have (enter the value without 
"0x" on the site I told you, feel the field "Convert", click on "to 
decimal")
Hex            Dec
F8000000    4160749568
F8FFFFFF    4177526783
So 4177526783 - 4160749568 +1 = 16777216
So 16777216 is 1000000 in hexadecimal
As a consequence for
 pci 0000:08:00.0: reg 10 32bit mmio: [0xf8000000-0xf8ffffff]
you will have
------------------------------------------------------------------------
    "/* reserve MMIO BARs of gfx for 1:1 mapping */
                     DWordMemory(
                         ResourceProducer, PosDecode, MinFixed, MaxFixed,
                         Cacheable, ReadWrite,
                        0x00000000,
                        0xF8000000, // the min value in hexadecimal
                        0xF8FFFFFF, // the max value in hexadecimal
                        0x00000000,
                        0x01000000) // value = max - min + 1 in hexadecimal value
----------------------------------------------------------------------------
Do the same steps for 
2 --------> pci 0000:08:00.0: reg 14 64bit mmio pref: [0xd0000000-0xdfffffff]
3 --------> pci 0000:08:00.0: reg 1c 64bit mmio: [0xf6000000-0xf7ffffff]
4 --------> pci 0000:08:00.0: reg 30 32bit mmio pref: [0xf5f80000-0xf5ffffff] 
That's all!
Ensure to put you vgabios-pt.bin in the required place. 
Compil and install.
My graphic card GT 440 works like a charm with nvidia 275.33. 
I've tried you 280.26 nvidia drivers but without any success. This 
driver version requires more ressoures. 
The GPLPV drivers for HVM works well too!