Accessing ~/Library in Open/Save dialogs
You have several options:

Make the ~/Library directory permanently visible in Finder and add it to your favorites in the sidebar. Then you can simply click on it in the Open/Save dialog. To make the Library folder visible, type the following commands in the Terminal.
 chflags nohidden ~/Library


You can navigate in a bash-like manner with tab completion. In the Open/Save dialog invoke Go to Folder... using:
⌘+⇧+G.

You can show hidden files in the Open/Save dialog. This way you can navigate to your Library via a parent directory which is in your sidebar. To toggle hidden files press:
⌘+⇧+.