Add Spell-Checking Dictionary Support to Pidgin Manually

Is there a way to install Spell-checking support manually?

Yes, if the installer isn't able to successfully download and install the dictionaries, you can do so manually.

Versions 2.7.0 and newer use the dictionaries available from the ​openoffice extension download site. You need to download the appropriate language extension file(s) (files are openoffice extensions *.oxt, which are just zip files that contain additional data). Once you have downloaded a dictionary extension file, you can rename it so it has a .zip extension and then extract the*.dic and *.aff files in it to <Pidgin Installation Directory>\spellcheck\share\enchant\myspell\(create the directories if they don't exist already).
If Pidgin is running, it will need to be restarted for new dictionaries to be recognized.

Versions older than 2.7.0 use Aspell; you can download both the Aspell core and a dictionary from ​the win32 Aspell website.