How to type a Unicode character by its number, e.g.
0x2E3B for Unicode character
U+2E3B (THREE-EM DASH) in Emacs?
On Emacs 23, type Ctrl+X 8 Enter and then the number, followed by Enter. Learned this from Emacs and Unicode Tips, which describes other methods too (Ctrl+X 8 Enter can be followed by Unicode name as well).
Note that U+2E38 probably does not show up unless you have installed Symbola or Everson Mono and defined one of them as the font to be used by Emacs. There might be other fonts that contain the character but the fileformat.info font support page mentions only these two.