BADI that is just migrated

Dear colleagues,

i have to use an BADI embedded in Transaction MIRO. It's name is INVOICE_UPDATE.

When I study the description in SE18 there's the entry: BAdI is migrated to an Enhancement Spot.

Where have I to do my usage, In SE18 or in SE20.

Can somebody help me and give me an explanation to this fact of migration.

Many thanks

Christian