The checklist task is deprecated. This approach might work for you:
 In BMIDE, create a custom form to act as checklist (as mentioned in your post)
 In the workflow template, use epm-create-form handler to create an instance of the custom form and attach it to your root task as reference or target
 use epm-display-form handler to show the form instance to user.
 You may want to (if required) validate the completeness of user responses in the checklist.