I imported the pictures manually by adjusting the old database table to suit vbulletins scheme. In the end I had generated three tables: vb_album, vb_albumpicture, vb_picture.
On a different thread concerning another import question (regarding picture comment hashs) you suggested using the datamanager. At that time I already imported the pictures. But it looked too complicated for me to use the datamanager. I only found the last two articles and I wasn' t able to understand their meaning.
Using the vBulletin Database Class
Creating Custom Datamanagers
Datamanagers: Objects as Data and Methods
Now I have read the first article. Although I was able to understand more than I did when reading the other articles, I have the impression that you need more knowledge about php and mysql. Since I know very little about it, it might be very difficult to adapt the articles to my import issues.