According to the documentation you can add a project from the registry or from a tarball url?
# add plugin from plugin registry
meteor add cordova:org.apache.cor
Updated 10/12/2015 for Meteor 1.2.
meteor add cordova:com.verso.cordova.clipboard@https://github.com/VersoSolutions/CordovaClipboard.git#03fe48b62411cbff22229ca13cc3ac8b282f7945
To add to the comment above... to get the @ part.
Before the @: Should be in the plugin.xml in the git repo with the key id.
Next, directly after the @ : https://github.com/VersoSolutions/CordovaClipboard.git
-Get this from the HTTPS link on the right side of the main github repo page.
Next, directly after the #:
-Go to one of the commits in github that you want, the number you need is the last number after 'commit'.
E.G. https://github.com/VersoSolutions/CordovaClipboard/commit/03fe48b62411cbff22229ca13cc3ac8b282f7945
The number would be: 03fe48b62411cbff22229ca13cc3ac8b282f7945 (The commit hash)