How can I show only an .htaccess file in the Finder?
To my best knowledge, you cannot selectively display dot files in Finder. However, if you just need a way to easily open them via Finder, you could create a symlink to the file in its directory, omitting the dot in the name, i.e.:


open Terminal, cd into your folder;
ln -s $PWD/.htaccess $PWD/htaccess.


You can then open the file by double-clicking the newly created link, select an editor in the link’s context menu etc. However, if you want to copy, up- or download your .htaccess file, you are stuck with Terminal, full display of all dot files, or temporarily renaming the file (to _htaccess, say).