You can remotely trigger a build by using the API
First you need to get your auth token:
$ curl -u [email protected] POST -d "" https://build.phonegap.com/token
Test it and retrieve your appid using the following command:
$ curl https://build.phonegap.com/api/v1/me?auth_token=[token]
After this go to your Github repo, open the admin and go to 'Service hooks'. Add a new WebHook URL (first option) and add yours
Save this and trigger it with 'Test hook'. When you would open:
https://build.phonegap.com/apps/[appid]/builds you will probably see a new build.