Briefly, yes it can.
A boot manager is included that is reputed to pick up the boot code for eah bootable partition and configure itself automatically (haven't tried it).
The Acronis boot manager (which looks easy to modify manually) WILL replace the original one so you would be well advised to have boot floppys or CDs for the other OSes before you start tinkering with it.
They do warn you about this in no uncertain terms. If you get stuck in Linux you an always use a Knoppix or any run-from-CD distro to start Linux and then chroot into your Linux and fixup GRUB or LILO from there.
In Windows you may need to modifyy boot.ini