Signing Limits for I-Expense

Is there any easy way to give a signer access to all cost centers rather than having to enter a record for each cost center individually?  We have a rather convoluted cost center set up which means almost any approver for i-Expense could end up approving expenses for almost any cost center so, ideally, I would like to be able to enter one record for the approver with their dollar limit and have it apply to all cost centers.