Here's how to do it with the Power Gum...
Get an empty reel spool
Make a loop of Power Gum about 50mm or so long (lengths vary depending on spool size and make)
Put the knotted end on your empty spool with the loop on the bottom inner face of the spool facing out near to your spool's line clip
Then wind your line on as you would do normally so that the loop remains facing outwards but is trapped by the line as you wind it on
Once the spool is loaded you should end up with a loop of Power Gum sticking out from the base of the spool near to the line clip
To use it, cast out to the required spot then take the loop, put it over your line and clip the loop into the line clip
Your line should now be trapped by the Power Gum and if you need to free it it's simply a case of unclipping the Power Gum from the line clip