I've been a part of the wedding entertinment business since 1995, and I've seen quite a few unique twists. Unfortunately, it is difficult to involve all of our guests in the ceremony, but there are some things that can be done.
I have seen candles, but rather than being lit as guests arrive, they are done similar to a unity candle during the ceremony. Everyone is given a candle as they arrive, but do not light it at that time. At a specific time during the ceremony, the bride and groom (or mothers if you like) will light candles of the persons sitting on the ends of a row (aisle side is generally better to use). Those people will turn and light the person next to them and so forth until the whle row is lit.
It would be important to work with your officiant and entertainer to provide some music during this time. It will take a few minutes, especially depending on the size of your group.
Another way is to do a flower petal toss at the end of the ceremony as you are pronounced husband and wife. This is easily done with paper cones at the ends of the aisles filled with flower petals. The officiant or your ushers can instruct guests to toss the petals at the end of the ceremony as you are walking out. Not as dramatic as the candles, but everyone does participate.
Hope these ideas are useful and spark some thoughts!
Sincerely,
Jason Spencer