The hex editor plugin mentioned by ellak still works, but it seems that you need the TextFX Characters plugin as well.
I initially installed only the hex plugin and Notepad++ would no longer pop up; instead it started eating memory (killed it at 1.2 GB). I removed it again and for other reasons installed the TextFX plugin (based on Find multiple lines in Notepad++)
Out of curiosity I installed the hex plugin again and now it works.
Note that this is on a fresh install of Windows 7 64 bit.