Implementing customized Access Control using Spring Security and ACL

Question

I need to extend an application developed in Spring platform. I have a number of tasks in different categories and a number of users in different groups. Each task, depending on its category, must go through different stages from beginning to completion (a predefined flow). At each stage, operations such as editing, deleting, or other customized operations may be applied on each task, depending on the user's access level. Some operations may not be applicable on some tasks. For example, it is possible to delete a task from the first category by a user from the first group, while a user from the second group can delete the task only when the task satisfy certain conditions. Similarly, a task from the second category cannot be deleted by the user of the first group. In addition new roles (new user group) or operations on tasks may be added in future. I want to use Spring Security for implementing the described access control but I'm new at Spring Security and ACL. I don't have enough time to study Spring Security comprehensively. I will be grateful if anyone can give me a quick and suitable guide for this implementation.