I think that install manifest will hold the information you need, previous EA installers with that was a case of opening up in notepad and changing the disk numbers for files.
So all you have to do is, find out how much of the .rar files you can have in the order of the installer (noted in the manifest file) to fit one DVD5 and then Put the rest on the 2nd disk. Just rename the 2nd disc the current label with 2 at the end.
Should work that way
Also you can leave out the spanish files if your just using the english installer, that will save a bit of space also.
EDIT: Why the big blank part above the folder listing the left tab?