You must have a vCenter Server key associated to your account (or a valid account).
Then you can simple download the bootable ISO from the vCenter Server downloads (see Enterprise Converter).
Note that the Converter version on the the ISO is named "version 4" but is quite the same as the old converter 3.0.3 (with same limitation).
Actually, it is possible to make a custom coldclone cd with version 4.0.1 on it. That will give you a hotclone solution working in a coldclone environment.
Just to let you know.