With regards to your question, there doesn't seem to be a way to mount it at a specific point, hover to mount it at boot, have you looked at the Make RAM Disk application?
Make RAM Disk is an application that provides an easy way to create, format, and mount a RAM disk in one shot.
If you add the application to your Login Items it will automatically create the RAM disk at each boot.
PS: Tested this on OSX Lion without any issues.
For completeness sake the following is from the Readme File:
How do I use it?
Just run it. By default, it creates a 64-MiB RAM disk named “RAM Disk”.
Can I have it create a RAM disk on startup/login?
Yes. Add it to your Login Items in the Accounts pane of System Preferences.
How do I get rid of the RAM disk?
Click on the Eject (⏏) button next to its name in the Finder's sidebar. Alternatively, use Disk Utility (in /Applications/Utilities) to eject it.
I want to create a bigger or smaller RAM disk or to create it with a different name. How do I do that?
Hold down the Option key while launching Make RAM Disk; it will present a window wherein you can change the size or name of the volume. If the “Save settings for next time” checkbox is checked, the settings you enter here will be saved (obviously); if not, they are forgotten just before quitting.
Remember: the Option key for the Options window.
Can I change the options without actually creating a RAM disk?
Yes. As long as the box is checked, the options will be saved, whether you create a RAM disk or not.