I'm currently trying to make a report that is similar, and have nested the table bmprdstr to an alias of its self using Item no and comp Item no with a Left Outer link, then linked to imitmdx for discriptions. I can email you a copy if you want.
What I have done only goes to 5 levels but its expandable up to 11. Its not very pretty (i'm only writing it to see if I can get a report of what I want and this was the 1st step.)