Install Windows with bootcamp using External hard drive

Windows won't boot from an external drive. It has to be internal.

 

Unless its x64, you should be able to boot off the install DVD and format the external and install but the install will want to reboot off the external which won't happen.

 

I'm not sure it's possible to boot off of the external drive to start the install.
You can try plugging in the drive and holding the option key when you boot, to see if it shows up as a selectable option.

 

That is the problem. The install process reboots a few times and when it reboots it can't reboot off the external. I don't think it can be done.

 

After the first reboot it doesn't need to boot off the external, all the necessary installation files will have been copied to the internal drive.
The issues are 1) whether the the computer will allow booting from an external drive, and 2) the installation program itself will be ok with this

 

But Windows won't boot from the external in the first place. Only DVD or internal. Why not burn the iso to a bootable DVD?

 

I'm assuming there's an issue with burning it to a DVD/booting from a DVD hence the OP wanting to install from an external drive.

It appears you are thinking the OP is wanting to install TO an external drive when that's not the case. They want to install FROM an external drive.

 

I realized this after my third post. Doh! Can't do it on a Mac because the install device needs to boot first and Windows can't do this on Macs (EFI?).

 

Can you can use Toast to create a startup disk drive for the harddrive. the computer will detect as a dvd/cd.