I should say that x-delta is not specific to PerfectGold.
It is a similar technology to ips except that it can patch >16mb files.
You can download the stand-alone x-delta patcher if you dont want to use PerfectGold, however PerfectGold is very easy to use for patching.
Tools > x-delta patching >Apply Goldeneye x-delta patch
choose base GE rom
choose x-delta file
save as new rom
Contrary to what sogun said about keeping the .rom extension you can save it as anything, although in the interest of standards I would avoid using v64 since that indicates byteswapped.
Trev