I would recommend first looking to see what efi chip it is.
If it is a simple SOIC8 package, the clip will work and if you want a GUI interface then use the blackcat. If you are comfortable with command lines, then the bus pirate, I would recommend v3.6 - as it is cheaper in cost over the v4
All you need to do is dump the 8mb rom, be sure to save a spare copy, open it in a hex editor and look for the lines that contain $SVS, there should be two areas within the rom, all you really need to do is FF out that line down to the next block of FF.
Only the first $SVS entry needs to be removed, yet both can be as well.
Be sure you pull the data sheet for the efi chip so you know the pin out.
It may be something like this
Make sure that:
pins 3, 7 & 8 are all connected to 3.3v
pin 4 to ground
pin 1 to CS
pin 6 to CLK
pin 2 to MISO
pin 5 to MOSI