To charge iPod shuffle on an iMac G3 or eMac computer, you need an optional accessory to reach the port, such as the iPod shuffle Dock or a third-party USB extension cable, both of which must connect to a high-power USB port to charge (Note: the USB Keyboard Extender cable that came with some Macs will not work as the cable connector will not fit the iPod shuffle). You can also use a USB power adapter or a high-power USB hub to charge iPod shuffle. These are all available from the iPod Accessories area in the Apple Store.
Be aware that if you connect iPod shuffle to your keyboard and it has no charge or a low charge, your computer may not recognize it. Because it isn't charging, the orange charging light also will never display when connected to the keyboard. If your computer doesn't recognize iPod shuffle through the keyboard, then charge it first using one of the above methods or by connecting to a high-power port on another computer.