WorkGuru supports the bulk creation of lead activities via a csv import template. The import template can be uploaded on the imports dashboard (Administration -> Imports)
Select the lead activities option:
Lead Activities Import Field Definition
|Lead number. Must match existing lead.
|Lead activity assignee - must match existing user's full name exactly.
|Lead activity type. Must match an existing activity type name exactly
|Lead activity due date. Format must be: DD/MM/YYYY
|Lead activity completed date. Format must be: DD/MM/YYYY
|Lead activity description/details.