Grateful Dad, definitely get a looper! Do it today. I followed Pete B.'s advice and got a DigiTech Jam Man a couple years ago, for practice, and it elevated my playing by about 1000%.
There are subtleties that only a looper can bring out for learning Garcia's technique. There are just too many notes sometimes to comprehend and a looper, connected to a CD player (or whatever; even can do video files, like a You Tube video), can cut through the extraneous sounds to get you Garcia almost solely. And you can chop up all of his phrases into snippets so that each tiny snippet gets you focused on those notes alone until you smooth out the phrase for yourself.
I just took on Wake of the Flood's Half Step last Saturday morning for the first time. Had to move a lot of files in the Jam Man to other locations to open the space for the loops to go in succession, and starting at position/file 74 got everything I need in by position/file 96. Now, when I get home from work, I sit down to it, dial in 74, give it a go, slow it down if I need to, and keep turning the dial to one file after the next as I work my way through. Nailed the opening notes (they're great, by the way), and have almost nailed the first solo completely.
The thing that makes it such an effective learning tool, other than that you can isolate a snippet and slow it down if you need to, is that you hear the snippet, alone, many times over, as you progress. By the time you know the song and work it up, you have the viewpoint of Garcia from that snapshot in his life thoroughly memorized. Once you work up the song, then you can take it in any direction you want with your own improvisation. But the essence is ingrained in you so that you have the structure and feel for quite some time.
Just an incredible learning tool.