Yeah, I know it's possible but I can't think of how. You can try setting the $HOME environmental variable when you run pidgin:
$ HOME=/blah pidgin
If that doesn't work, then an easy solution is to use a symbolic link on Linux:
$ ln -s /mnt/windows/...../pidgin /home/you/.pidgin
When I run pidgin would I have to specify the environment every time? I've been Googling but to no avail, so I'm at a loss.
You'd have to put it in the shortcut or whatever when you run it, yet. I'm not positive that pidgin respects $HOME, though, so you'd have to test it.
The perfect solution for just about everything.
Certainly not very useful for me here. I'm going to have an accessible filespace for both Windows/Slackware to r,w,x and I don't want to have to manage both individual filesystems when I do stuff. So symlinks wouldn't be super helpful for me, if I understand them right.
A symlink will definitely work from the Linux side, because you can point your config folder wherever you want. I know Windows has some kind of symlink concept as well (I think they call them "junctions"?), but I'm not sure if they can go to different drives.
Worst case, you could mount your Windows NTFS drive read/write from Linux and use the Windows drive directly. It's less than ideal, but it'd likely work.