That's one way, the other is compression grommets. You can buy them at most mobile sound shops. If you look in my Photo Gallery on my web site, in Other Installs, and bring up the last page (7). W7LV10 is what you're looking for. This saves the need to have to install the extra connectors.
Remember a couple of important points. High strand count wire (welding cable for example), requires that the connectors either be crimped on or solder potted. This is necessary to minimize solder wicking into the cable and weakening it. The other is, don't use the body as a ground return. Run a separate cable.