From what i understand he wants to create a seperate Google account with all the Google App Engine stuff under so he can share this account with everyone who needs to access the Instance.

There is a easy way of doing goto the app engine management and on the left you will find a option to change permissions to be exact ( Administration->permissions)
There you can invite other people gmail accounts to manage the instance and you can specify exactly what they have permissions to change and do.

If you are trying to create this using Google Apps account http://www.google.com/Apps and you cant connect it up to google app engine and cant use another phone to verify the account then you will have to open a support ticket with Google.

The Reason why they only allow one cellphone number per google apps account is because they have a free zone(or something similar to amazons freezone) and do not want people abusing it byt being able to launch as many servers as they want for free.