You don't need your EE profile credentials to create OINP application.
You require the following from your EE,
1. EE profile number
2. Validation code
3. NOI message
(Data shouldn't mismatch from your EE)
Even though you don't need other than these 3, consultant must share the credentials with the applicant. If they don't share login and passwords, it may(or may not) sometime lead to several problems later. You may not know what they have declared or what they missed. Think what would happen, when he tries to charge you extra or something else!!!
http://www.cic.gc.ca/english/information/representative/index.asp
CIC's information about representatives/consultant