How to create assignment block which show DATA in TREE format

Hi Frds,

Please suggest. How can we achieve the assignment block which is in TREE form ,Might b its not fully TREE form there will be some easy way to achive my tesk. I have a custom table with contain User id and name of each Role(ROLE_NAME).   Below is the tast example.

Assignment block display different lavel of approver list.

ROLE_Name is a fixed text.

Please help how can we achive this task.

Thanks

Imran