There was a web-based editor for BPEL4Chor based on the Oryx framework offered at http://oryx-editor.org/backend/poem/repository/new?stencilset=/stencilsets//bpel4chor/bpel4chor.json. However, the hosting service is currently down as Oryx became Signavio.
BPMN+ as extension of BPMN 1.0 supporting all constructs offered by BPEL4Chor has been described. BPMN+ diagrams can be transformed to XPDL4Chor or directly to BPEL4Chor.
Try a preview version of the editor at http://oryx-editor.org/backend/poem/repository/new?stencilset=/stencilsets//bpmnplus/bpmnplus.json. If you want to save a model, you have to login at the Oryx main site. A model gets saved private. You have to explicitely login and enable sharing to enable public viewing of the model.