Here is how I did it recently, and it has so far has worked great!
- Get another empty spare reel of the same size or larger spool that has no line on it and attach it to the bottom piece of another spare rod.
- Fill the spare spool/reel with your braid any which way you can, manually by hand, just reel it on loosely from the original packing, etc...
- Once it is all on, add mono if using mono backing or tape to the reel you plan on putting it on.
- Attach the end of the line from the spare reel to the reel you want the line on.
- Set the drag on the spare reel to about 4lb.
- Have someone hold the spare reel half piece rod, or wedge it between a fence post, anything to create a tension.
- Reel it in from the reel you want the line on!
- Ther tighter the spool on the spare, the tighter it will go onto the reel you want.
Just my 2c, any additions welcome. I must admit, it is much easier just to go to a bait shop though!!