The package only contains an importer for the 3.x versions. However, Kier has mentioned on the forums that Paul's importer for the 4.x series , as Russ has pointed out, does the job well, and there is mention of it in the Help manual as well. Of course, my own experience was the same as well.
I hope you're going for a test migration first. Good luck, Saud.
Using Paul M’s vBulletin 4 Importer I ran through an import from a year-old backup of the main boards, importing around 9 million posts without a hitch. On our test server the import took just over 24 hours.