In those multi image installer files OBH 5.0 does not excist since it still not released official.
So you have to do it manual.
From your OBH 4.4 backup with ftp this folders and files.
/etc/tuxbox/configs (here is your oscam config files)
/usr/camscript (here is the start and stop script for your oscam)
In folder /usr/bin you find the oscam bin files they can be named more then jus oscam bit it does you need.
Now in your OBH 5 image copy the backup files to same location with FTP
Important is that you give the correct file permission to the oscam bin files and files inside your camscript folder
They should be set to 755
If you use FileZilla as your FTP software just right click with your mouse in the files to open the menu
Choose in the bottom "File permission" and in the text box just change to 755 and press OK button