Brewing a really spot-on Belgian-style Wit is almost impossible without mashing. That said, you can get pretty close with your standard procedure and setup.
Here's an easy recipe that'll at least remind you of Witbier:
1 1.5kg tin of Coopers Wheat Beer "beer kit"
2 lbs Wheat Dry Malt Extract (DME)
1 ounce Saaz or Hallertau or Tettnang hops
1 ounce package Bitter Orange Peel
1 ounce Coriander Seed
2 grams Paradise Seed
1 sachet Brewferm Blanche yeast
(You probably can't order from the links provided but I wanted you to know what the products looked like for when you go to get ingredients)
1. Bring at least 2 gallons of water to boil. Remove from heat, stir in DME. Bring back to boil.
2. Add hops. Boil 20 minutes.
3. While boiling, crack coriander and paradise seed roughly in a coffee grinder, mortar & pestle, or in a ziploc bag with your Cooper's tin.
4. Add spices. Continue boiling 10 more minutes.
5. Remove from heat. Cool.
6. When cool pitch yeast.
Follow your normal bottling procedures after fermentation is complete.