If you use BeOS 5.01 or a version of OpenTracker released after July 2000, this tip is irrelevant — just open the Mount Settings panel (right-click on Desktop | Mount | Mount Settings) and select „Previously mounted disks.“ The old tip remains below because it still works and some people like to do things by hand.
As you know, you can use the Mount Settings panel to control whether various kinds of volumes are mounted automatically at boot time. But what if you want to get more selective than that? For example, you may have half a dozen mountable partitions on your machine (both BFS and those from other operating systems), but only want two of them mounted automatically at boot time — your boot volume and your data/MP3 volume.
To do this, tell the Mount Settings panel to mount Only the Boot Disk during boot. Then add lines like this to /boot/home/config/boot/UserBootscript:

mountvolume booboo
mountvolume esther

and so on.