How can we validate or restrict coding for POET when users create requisitions

We are finding we are getting a high volume of errors when users create requisitions that require POET coding needed for PPM and EPM allocations. For example, if a user codes a requisition to the CIP general ledger account, we want them to be required to use POET. We have various other code combinations required for both capital projects and pool projects used for cost allocations. I understand that general ledger cross validation rules cannot be used for POET. What alternatives are available? Thanks for your help with the critical operational issue we are having.