How to run a concurrent program by a custom Manager

Step 1: Create a custom concurrent manager.
Follow Doc ID 170524.1 (How to Create a Custom Concurrent Manager)

1. Navigate to Concurrent > Manager > Define.
2. Manager Field: Custom Manager.
3. Short Name: CUSTOM.
4. Type: Concurrent Manager.
5. Program Library - Name: FNDLIBR.
6. Enter desired cache (such as "2").
7. Work Shifts: Standard.
8. Enter number of Processes (e.g "6").   <= here you can modify it later
9. Provide Specialization Rules
   (you can include or exclude program, id, user, types or combination).
10. Save.
11. Navigate to Concurrent / Manager / Administer.
12. Activate the Custom Manager.

Step 2: Assign concurrent program to a custom manager 
Follow steps in Doc ID 2268941.1: How To Set Concurrent Program To Run Exclusively From A Custom Manager
1. From System Administrator Responsibility navigate to:
  a. Concurrent > Manager > Define
  b. Query up the Custom Manager (such as "Long Run Jobs Manager")
  c. Click on Specialization Rules button
2. In the first column, select to Include
3. In the second column select Program for Type
4. In the third column select the Application that the concurrent program was defined to run under
5. In the fourth column select the concurrent program name.
6. Save.
7. Query up the Standard Manager definition.
8. Under the Specialization Rules Exclude the same program and Save.

Additional documents on this topic:

Doc ID 343575.1: How to Determine Which Manager Ran a Specific Concurrent Request?
SQL> select b.USER_CONCURRENT_QUEUE_NAME
from fnd_concurrent_processes a,
 fnd_concurrent_queues_vl b, fnd_concurrent_requests c
where  a.CONCURRENT_QUEUE_ID = b.CONCURRENT_QUEUE_ID
 and    a.CONCURRENT_PROCESS_ID = c.controlling_manager
 and    c.request_id = &request_id;

Doc ID 344011.1: How Do I Find Out Which Concurrent Manager Processed A Concurrent Request/Program.