If you press "HTML" button in the editor, you can edit raw HTML (and find a way of implementing what you want in HTML).
In this case, you want to use
to end your lines. Like so:
<p>Hickory Dickory Dock<br />
The Mouse Ran Up the Clock<br />
Blah blah blah</p>
Use "Address" format and then make it non-italics.
EDIT: Huh, you can toggle the italics button, but that doesn't make it display right. Nevermind.
The comments section has the handy little "help" feature (confusing though its title may be) that explains how to format. I can't figure out where that section is for actual articles, which use completely different syntax.
In particular, I don't know how to post a I'm having trouble posting "lyrics", i.e something that's supposed to look like this:
Hickory Dickory Dock
The Mouse Ran Up the Clock
Blah blah blah
except without the paragraph breaks in between. The "preformatted" present sort of works, but makes everything tiny. (Also, when I actually submit, it seems to randomly make some sections of the preformatted stuff large, so it ends up looking really unprofessional)