Watch the One Finger Double-Stops online guitar lesson by Brad Carlton from Essential Techniques
When moving from one chord formation to another and changing position, I use a technique called prepared guide fingers. This simply means that instead of hopping from one fingering to another, I gracefully move into the new fingering far in advance of completing the position change, and I utilize guide fingers as a means of security and dampening. This also allows the hand to empty all muscular tension in between chords.
Part two of this lesson will show you how to in effect, grow some spare fingers. The technique of playing two adjacent strings in the same fret with the same finger frees up another finger for adding other notes. This is great for chord melody as it allows you to sustain voices like a piano but it is also a means for accessing long stretched out close voicings with less contortion and intonation issues.