If the applicant  completed an Income-Driven Repayment Plan Request as part of a Direct Consolidation Loan Application, he or she will click on "Direct Consolidation Loan Applications" under "My Loan Documents" to locate and provide you with the Co-sign Code you need.
and it is the same place to sign in for both?
Yes, you log in to the Co-sign Income-Driven Repayment IDR Plan Request
can either one of us do it?