EIM : How to populate S_EVT_ACT contact columns.

This was my last task, populate primary contact columns (target_per_id and pr_con_id) in activities table (s_evt_act). So, I start looking for some eim table to do my job, and after looking my entire references I didn't find one.
And why didn't I found one? Because, there are no explicit way to do it. So what you have to do is :

1. Populate s_act_contact intersection table with the desired pair activity/contact using EIM_ACTIVITY1.
2. Set ACT_TARGET_PER and ACT_PR_CON (in EIM table) to 'Y'.
3. Run EIM task.

Internally EIM will implicitly fill s_org_ext columns for you. Below you can find an ifb excerpt that do what we desire.

[Update Activities]TYPE = IMPORT
BATCH = 4511
TABLE = EIM_ACTIVITY1
ONLY BASE TABLES =  S_EVT_ACT,S_ACT_CONTACT