You can add special character buttons on top of the search box.
When a user clicks on a button, it will insert the character into the search box.
In the Webonary settings click on the tab "Search". You will find a textbox under "Special character input buttons" where you can enter all your special characters separated by commas.
You can also choose in which font the characters should appear (you first have to upload your dictionary data with the style sheet in order for the fonts to appear).