This is a piece of cake if you’re only after the terminal syllable, but given that the EM-pha-sis is on the first SY-lla-ble in NU-thing, that strikes me as unsatisfactory.
The only way I can do it is to allow a lisp:
Theven year-old Thally,
Who’th jutht lotht a tooth,
Ith futhing, futhing, futhing
Over nothing, nothing, nothing.
I would love to see any other solutions.