I solved using ITopologicalOperator:
Dim pGeom As IGeometry
Dim pTopo As ITopologicalOperator
Set pTopo = plyne1
Set pGeom = pTopo.Intersect(plyne2, esriGeometry0Dimension)
Dim ppoints As IPointCollection
Dim ppoint As IPoint
Set ppoints = pGeom
Set ppoint = ppoints.Point(0)