writing vertically in Japanese

[Ionutz Borcoman <borco@borco-ei.eng.hokudai.ac.jp>]

Hi,

Can I write vertically in Japanese with XEmacs and pLaTeX (LaTeX with
Japanese support) ? Can I mix vertical/horizontal contexts ? Is there
any other editor capable of this, if XEmacs is not able ? If XEmacs can
do this, then please explain me !

TIA,

Ionutz