I am new to the forum and I just saw your question. Yes, you can so it exactly like you stated. To put the initiator name in the Custom Title 1 field, you have to execute the code below. You can set the script to run on a schedule.
UPDATE ITWORKITEMS
SET ITWORKITEMS.WICUST1 = ITUSERS.DISPNAME
FROM ITUSERS
WHERE (ITWORKITEMS.WIORIGPTUID = ITUSERS.USERUID)
Actually, you can just put WIORIGPTUID in the WICUST1 column and sort on WICUST1. The data in WICUST1 column will look like garbage but it is the same as USERUID value on the ITUSERS table. When you sort on this, you will in effect be sorting the Initiator column.