Prall with alteration

You can use the prall line from the lines palette. click the note where you want it then ctrl +click the next note and it will only be applied to one note. You can then add the accidental from the accidentals palette. Select the prall and double click the accidental. It looks right, but doesn't play correctly. If the prall ends up too long you can edit it like any other line (double click and drag the square).

Note: the prall line is in the advanced palette.