FilterKeys-Can this be applied to only the non-alphanumeric keys?

My dad is a fast typist, but he has a problem finding
himself in unexpected places in his documents and with
strange formatting becuase, we are guessing, he is
inadvertantly hitting extra keys. He doesn't want to slow
all of his typing down with the filterKeys accessibility
option, but it would be great to aplly that to the INSERT,
CTRL,ALT, etc keys. Is that possible? How can I do it?
Thanks in advance,
Eve