Windows Text Editor With SCP Support and No Install

Komodo Edit will do this I think. (Komodo Edit Portable).

It's free and has a very nice feature set.

vim is another option:

uses pscp (from putty) to do the 'edit over scp' part, read more:

• http://vim.wikia.com/wiki/Using_PuTTY_pscp_with_Vim