Snagly: To be honest with you I just slide my mainline which is braided through the float and tie the TUFF line onto a snap swivel and thats all. I have probally jinked myself so that next time I am out fishing floats I am gonna wrap my mainline around a tree or a rock or something and not be able to break it off.
If you feel safer attaching the float to mono it is very possible just to tie the mainline to a barrel swivel then tie in a piece of mono and slide the float onto that but you would probally want to tie in a heavier piece of mono for the section that float is because if you snag up you make it very hard to lose your float when you break off.
If you are good at nots which I AM NOT you could tie a section of mono to the mainline with say a Bimmini twist or something along those lines.
Ryan