When you decide to install Linux anywhere, you ned to have a plan. In your case you found out, after the fact, that your system does not support booting from USB. However, most "new" laptops can boot from USB, so my first question is, what make and model laptop is this?
 
Secondly, no, you can't create symlinks as you describe. what you need to do is have a way to boot your FC4 installation. This topic was covered recently in another thread, but to recap briefly;
 
1. The default Fedora installation process assumes that you are installing it to an internal hard drive, namely the main hard drive in your system. So, if you accepted all the default options, then FC4 assumed that this was the only hard drive on your system and proceded accordingly.
 
2. The default FC4 kernel does not load the modules (drivers) needed to boot from an external USB drive. There are special instructions for this.
 
In order to boot from an external USB drive, you need to have some sort of a bootloader, either;
 
1. The ability to boot from an external USB drive in the bios,
 
2. An installation of Linux already on the system that has the grub or lilo booloader that your current installation can be added to, or;
 
3. A boot CD that allows booting a Linux distro.
 
However, your problem is that by choosing the expert mode to install to the external USB drive, the proper modules were loaded to see the drive. That's why they call it "expert mode" - which assumes the user knows what they are doing to set up the installation properly. Once you install to the USB drive, you need to rebuild the initrd file with the USB modules needed to be present during boot to sense the external USB drive and boot that drive properly. The initrd file holds the instructions needed to load the proper modules at boot.
 
But, let's see what you have before we go on. Are you sure that the laptop can't boot from a USB drive?

danleff thank you for the fast reply. I have an HP dv5130us.
AMD Turion 64 ML-27 2.0GHZ
120GB HD
1GB RAM
External HD 40 GB
I did a little searching for a boot loader cd before I posted this topic but no luck. If I got the boot loader cd could I then rework the initrd?
 
Also for the install process I refered to the following link
http://www.linuxcompatible.org/Install_Fedora_Core_4_on_USB_hard_drive_t34055.html

I found Fedora a little funky about doing this. it all depends, I found, on how you set up the partitions during the installation.
 
Apparently (which has been verified by another user who posted his experience with this) it all depends on if you accepted Fedora to be installed using Logical Volume Management partitions or not.
 
If you format the drive/partitions with the traditional linux partitions, not using LVM, then the USB booting works properly. Fedora is also able to resd the partitions better when you boot into rescue mode and modify the initrd file. I ran into this with FC5 trying such an installation.
 
But, in terms of your system. what are the options in the bios for booting various media?
 
If you go into the bios (F10 at boot time) and navigate to the Advanced Menu-->Enable Multiboot area, what are the media booting options that are offered to you to set? The online users manual is not very specific about this.
 
Or, look at your actual users manual (hard copy). Does it list the possible options under the advanced menu for booting different media? Does it list some options like;
 
USB-HDD
USB-FDD
USB-ZIP?

OK! I think I might have enough info to get this going. I was reading my user manual and found that USB legacy support comes dissabled by default. I haven't had a chance to test enabling it but, from what I understand about legacy, I should be able to boot to usb devices.
 
By the way, I had read before hand that I should do diskdruid to avoid LVM. My partition setup is as follows.
 
/boot ----- 100MB ----- ext3
/ --------- 3400MB ---- ext3
----------- 500MB ----- swap
extended
/wshare --- fill ------ vfat
 
Again thank you so much for your help. Maybe I won't have any more questions for a while.