We incorporated a sand ceremony into our wedding. It was a traditional wedding overall, but the sand ceremony can be done in any context.
You can also go through the whole "official wedding" process, just without the license and officiator. Change the vows as necessary to match your arrangement.
There seems to be some good info here: http://www.nonreligiousweddings.com/handfasting.html
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker