Problem solved. I ended up creating an API
ad_proc bug_tracker::get_items

the main part of it is:

set role_id [workflow::role::get_id -short_name $role -workflow_id $workflow_id]

set user_id [lindex [lindex [workflow::case::role::get_assignees -case_id $case_id -role_id $role_id] 0] 3]


the rest, i followed your tips above in this thread to get the parameters here and there

Thanks a lot!