A label really contains only one row of data, so you can't force a new label unless you can create a second row. You could potentially use a command that uses a union statement as your datasource. You would add the notes up to a certain length in the first component of the union statement and then add additional unions for each additional length, e.g., the first row could contain left({table.field},100), and the second one could contain mid({table.field},101,100), the third could contain mid({table.field,201,100), but you would be duplicating rows where the length extended beyond 100. I'm not sure of the function you can use in a command that works like "mid"--possibly locate().
-LB