Edit Export Table in PEMaker whitout corrupting the file

I am using PEMaker to add these two functions in the core of Windows XP SP1 DecodePointer and EncodePointer, because a lot of software requires it like New Moon from roytam1, and all versions of Firefox 13+, I want to make a little KernelEX for Windows XP SP1 that can run SP3 software.
All good up there, but when I save the export table, the import table is corrupted since those two ordinals occupy part of the import table and therefore the dependency walker sees it as a corrupt file, but when I change the addresses of the import table does not move the table and extends the capacity, it only changes the line of code in which it begins and it is also corrupted.
With PEMaker I was able to successfully add in ntdll.dll; RtlDecodePointer and RtlEncodePointer since it had no import table.
Does anyone know how I can add one or more instructions to a file with both export and import tables, without making them corrupt.