You shouldn't have any problems. The video someone made doing it with a Doyle's is dead on. Make sure all tension is off before opening it. There will be a little but it won't hurt anything. It seems like it could be complicated but you just have to pay attention to what you're doing.
As soon as you open it, mark the drum so you know which is the top side with an arrow to indicate the direction of pull. If you're holding it with the pull side to the right, it comes out clockwise.
On new line, put the plastic ball on, tie your clip and then thread other end back through case before tying and winding line onto the spool. If you're splicing your clip on the end, make sure you do a good taper or it'll hang a little when the last 6-8" retracts. After you install the new line, don't pull on the metal band that comes out of the spool (it'll come out some and you won't be able to get it back in.)
Wind the line by hand flat so you don't introduce twists into the line.
When you have all the line installed and the spool is back in the case, pull a few feet out and manually wind it around the spool. Test it to make sure the winder is pulling the string all the way into the hook. If not, pull out some and hand-wind one at a time until it positively retracts.
Most you'll get onto it is about 30'. You can put more line on but when you pull it out, only 30' will come out. Spring is maxed out at that point. I put about an extra foot on so that there's still some left on the spool at full extension.