There are several sites out there that show you how to do this but since I need a bootable cdrom for my i386, I used this method.
1. To start you will need to download and install a program called "mkisofs". This is the program that will make the ISO image that we can burn to a CD. I have only used this on NIX type systems I am not sure if it is available for windows. Search freshmeat.net if you need to find it. Or if you have a Debian GNU/Linux system (like me) you can just type "apt-get install mkisofs".
2. Next we need to make a few directories which will be the file system hierarchy. The top directory will be called "OpenBSD". The next directory down will be the version number of the OpenBSD release (4.1). The next directory down from that will be the architecture type (i386). In the architecture directory is where the install files will be going. Here is a quick example of making the hierarchy in the /tmp directory. Please switch to the root account to perform any steps if necessary.
/tmp> mkdir -p OpenBSD/4.1/i386
/tmp> cd OpenBSD/4.1/sparc
3. Now stay in the "i386" directory. This is where we are going to put our install binaries. Find a mirror and download the following binaries (below) from the i386 architecture directory like ftp://ftp3.usa.openbsd.org/pub/OpenBSD/4.1/sparc. The following commands will download the entire remote directory to the current local directory if you have the program wget installed.
/tmp/OpenBSD/3.8/i386>
wget --passive-ftp ftp://ftp3.usa.openbsd.org/pub/OpenBSD/3.8/i386/*
File: CKSUM 1 KB 3/10/2007 11:53:00 PM
File: INSTALL.sparc 85 KB 3/10/2007 11:53:00 PM
File: MD5 1 KB 3/10/2007 11:53:00 PM
File: base41.tgz 38847 KB 3/10/2007 11:53:00 PM
File: boot 54 KB 3/10/2007 11:53:00 PM
File: boot.net 54 KB 3/10/2007 11:53:00 PM
File: bootxx 10 KB 3/10/2007 11:53:00 PM
File: bsd 3078 KB 3/10/2007 11:53:00 PM
File: bsd.rd 3301 KB 3/10/2007 11:53:00 PM
File: bsd.scsi3 3078 KB 3/10/2007 11:53:00 PM
File: cd41.iso 3824 KB 3/10/2007 11:53:00 PM
File: comp41.tgz 60976 KB 3/10/2007 11:53:00 PM
File: etc41.tgz 1215 KB 3/10/2007 11:53:00 PM
File: floppy41.fs 1440 KB 3/10/2007 11:53:00 PM
File: game41.tgz 2617 KB 3/10/2007 11:53:00 PM
File: index.txt 1 KB 3/10/2007 1:33:00 PM
File: installboot 94 KB 3/10/2007 11:53:00 PM
File: man41.tgz 7205 KB 3/10/2007 11:53:00 PM
File: miniroot41.fs 6144 KB 3/10/2007 11:53:00 PM
File: misc41.tgz 2239 KB 3/10/2007 11:53:00 PM
File: xbase41.tgz 10421 KB 3/10/2007 1:33:00 PM
File: xetc41.tgz 90 KB 3/10/2007 1:33:00 PM
File: xfont41.tgz 32459 KB 3/10/2007 1:33:00 PM
File: xserv41.tgz 9562 KB 3/10/2007 1:33:00 PM
File: xshare41.tgz 2027 KB 3/10/2007 1:33:00 PM
This list includes all the files in the 4.1 directory.
4. Now we will make the ISO image. We will go back up to the "OpenBSD" directory and execute the "mkisofs" command with some options. We will be using the cdrom41.fs to be our boot image for the CD. If this image has boot problems on your computer then you can try the floppy41.fs as your boot image. Please see the mkisofs man page for what the options are for. Please note that if /tmp/OpenBSD/OpenBSD41.iso exists and you run mkisofs again it will simply append the new image to the old image. Thus making the new image twice as large with illegal directories. Ok execute the following commands:
/tmp/OpenBSD/4.1/sparc> cd ../../
/tmp/OpenBSD>mkisofs -vrTJV "OpenBSD41" -b 4.1/sparc/cdrom41.fs -c boot.catalog -o OpenBSD41.iso /tmp/OpenBSD/
5. Now you should have a ISO image named "OpenBSD41.iso" in the /tmp/OpenBSD directory. Take this ISO image and burn it to a CD using your favorite burning program. Enjoy!
