Answer:
An imperfection is considered as a load and is transferred via the interface of the load case. Provided that the interface to the model has already been imported, the interface to the loads (ILoads) followed by the interface to Load Case 1 (ILoadCase) will subsequently be imported, if it has already been created:
' set loadcases
Dim iLoads As iLoads
Set iLoads = model.GetLoads
' get load case
Dim iLc1 As ILoadCase
Set iLc1 = iLoads.GetLoadCase(1, AtNo)
' define imperfection
Dim imperf As Imperfection
imperf.Comment = "test"
imperf.Direction = LocalZType
imperf.Inclination = 200
imperf.no = 1
imperf.ObjectList = 1
imperf.Precamber = 300
imperf.PrecamberActivity = ActivityAccording_EN_1993_1_1
' set imperfection
iLc1.PrepareModification
iLc1.SetImperfection imperf
iLc1.FinishModificationThe data of the imperfection are then filled out first, here for Member 1, then transferred within the Prepare-/FinishModification block of the Interfaces load case.