ok, since people are having a hard time with this, I am going to explain how to properly put OS X on their beige with XPostFacto.
First, you are going to need XPostFacto from here. When you got that, you are going to need to install OS 9 on the system. but before you do that, if you have a drive larger than 7.6GBs, I would suggest that you partition it so that OS X resides within the First 8GB. I have done it without doing this, I mean, install a minimal 9 and then 10 right after it, but it can sometimes mess things up on a machine (hasn't done anything to mine 
)
After you install 9, you *might* want to install the upgrades (like getting the system all the way to 9.2.2). After you do that, you are going to decide what you are going to install (i am doing 10.3 and 10.4) (note: It is suggested that if you have problems with the install, you might try a dvd drive?)
Installing OS X
Ok, here we go...
Put in the first CD (or DVD) and go into xpostfacto and click the partition that you want to install it on (You will need to make it on the first partiton that is less than 8GB) and click on "options". Make Sure both "Use Verbose Mode" (for diagnostics), and "Use old NDRVs" That is going to force it to use the old Video Drivers. (DO NOT HIT "ENABLE L2 CACHE" it will screw up the system!)
get out of that box, and make sure the drive you are installing onto is highlighted then click "restart now"
Continue to install OS X. BUT! when it restarts the first time, hold down the option key and go Back into XPostFacto.
Go to the menu item called "install" and go down to "everything". let it install the stuff, and then highlight the OS X box and click restart now. Hopefully you won't have a problem...
IF you need anything, i will watch this forums, so post your problems
I've got 5 beige G3's so I have a little experience with this. I've had to change any options in XPostfacto like you suggest, though. One thing I have noticed, though, is that it's a good idea to install OS X on a drive set to Master, if you have multiple drives. Trying to boot OS X from a slave drive can often cause problems.
The 8gb partition limit only applies to IDE/ATA drives. If you're working with a nice big SCSI drive, you don't need to worry about it. (was a beige g3 warrior for a while)
My Beige (G3 266, 4 GB, 384 MB) recently developed some problems with it's HD, resulting in hangs and such. I put in a new 10 GB drive, partitioned it accordingly, and tried to use Carbon Copy Cloner to make a copy of the existing install on the new drive.
No dice. To many errors on the disk to get a bootable system.
So... I cheated.
I brought my trusty Gen1 5Gb iPod up to work, plugged it in to my eMac, and installed OS X v10.3.9 onto the iPod. I then applied all appropriate updates (so that I wouldn't have to do so over my lovely dial-up connection at home), downloaded and installed any apps that I think I need, installed OS 9.2.2, and took my iPod home.
Since I have a firewire card in my Beige, I booted into Mac OS X on the bad drive, ran Carbon Copy Cloner, and cloned the iPod install of Mac OS to the new drive. Used XPostFacto 4 to install the appropriate boot thingies and to bless the OS 9 install, then copied the stuff I would need from the bad drive to the extra 2 Gb partition on the 10GB drive.
I shut down, removed the bad drive, stuck a 9GB SCSI in there with the 10 GB IDE, and booted.
It's alive!
I don't necessarily recommend this method, but I had to share it. Carbon Copy Cloner (www.bombich.com/software/ccc.html) is a wonderful tool.
For anyone getting the Beige G3 Black Screen problem I've solved mine by using a flat screen (panel) monitor instead of using a crt monitor.
Some crt monitors seem to lose the scan (resulting in a black screen) probably because osx isn't setting up the rage chip properly for some crt monitors.