How to display only selected invisible files on mac osx 10.+?
You can either show all hidden files or none, there is no in-between.

The only way that I know of to easily access dot-files is to create a link to a visible file. For example, you could create a link from ".htaccess" to "htaccess.txt" and then "htaccess.txt" would be visible

Here's a way to make those link for all of the .htaccess files in the current directory and all subdirectories in Terminal:

find . -type f -iname .htaccess -execdir ln -s {} htaccess.txt \;