Booting from hard drive is not really more difficult that booting from CD. The only thing really important is that your hard drive has to be correctly prepared. Take a look at Section 3.3, “Making a bootable partition” to learn how to prepare it.
Start the box and enter the BOOT_ADMIN mode. (Section 1.1, “Entering the BOOT_ADMIN interface”)
There are two options from there: either you know the
full PATH to your hard disk device,
then you can jump to next step, or you don't.
In this last case, issue a search ipl
to list all available bootable devices.
You can also specify
search [PATH].
For instance if you want to search the Single Ended SCSI bus:
search SESCSI
Take a look at help search for details specific to your box.
Once you know the full PATH to your hard drive,
you can issue a boot <PATH>.
That's all. If everything goes fine, it will start booting the kernel
as setup by PALO (see Section 3.3, “Making a bootable partition”).
Real life example:
boot scsi.6