Sawsong, what you are refering to is called "isolating the branch".
Sure, use both ends of the throwline, dont be afraid to add more weight to like 2 or 3 throw bags. You should always have 2 throwlines and a few bags anyway coz you will get stuck one day.
Check out this swing technique at the beginning of this video using double throw bags midline.
Quality is a little poor but you can see what goes on.
http://www.palmtreeservices.com.au/v...ellinggums.wmv 11mb WMV