You can split hunks until they're consecutive lines. You can't split more granularly than that with -p. You'd need to edit the patch, either directly or with git gui or similar.
I resisted the edit option of git-add -p for a long time because I was afraid of messing something up with a low level tool... big mistake! So easy to use!
Plus if you make a patch that doesn't apply it will just error out and you can try again. And if you add anything extra by mistake you can easily back it out with something like git reset HEAD <file> or git reset -p