OK guys i have got it, thanks to pokey006's help from another forum, i now have the exact method that should get all your voltage changing option working in ati tool. You can check in rivatuner when you increase your gpu voltage and it should now change as its supposed to.
Get atiflash 3.09 and put both files on a floppy
Next download sapphire xl bios from techpowerup.com and throw that on the floppy as well, i changed the name of my bios to a short name so it works easy in dos such as sapxl.bin
Next you can download Bgnomes modified bios from here if you have a card that unlocks to 16 pipes like mine.
x1800GTO Modified Bios
If yours does not unlock to 16 then you can just use your default GTO bios for this step.
Anyway copy that bios to your floppy as well, i named mine gtomod.bin
And last thing you can make a flash.bat file by just making a new text document and inserting the lines exactly as shown here
atiflash -newbios -f -p 0 sapxl.bin
atiflash -f -p 0 gtomod.bin
after you put those 2 lines in the text file, save it and then rename it to flash.bat and of course throw that onto the floppy as well
You should now have 5 different files on the floppy, 2 bios's, 2 files from ati flash 3.09 and also the flash.bat file.
That's it now you can go boot to dos and run the flash.bat file and if all goes well you should have a x1800Gto thats able to change all voltages and show temps in AtiTool.
Thanks Goes to Pokey006 and Bgnomes for their help on Getting this all to work.
Last but not least Flash At Your Own Risk!
Have A Nice Day!