Ye-e-e-s (= cautiously). Paragraphs have a 'lines' property, and you should be able to add something using
someParagraph.lines.insertionPoints..contents = "123!";
(untested) I don't know what happens when you change a lot right after eachother in the same paragraph -- it might be the 'lines' (which are pointers into the actual paragraph) are not recomposed immediately when you add text in front.
If your lines are actually all one-liners, where each paragraph is a single line, it's no problem at all.