See documentation for Surround Selection to specify character toggles in the options dialog for Visual Assist.
Visual Assist build 1940 through 2083
By default, the Surround Selection feature of Visual Assist responds to the characters ' / * { # (
You can tell Visual Assist to surround on a subset of the characters. When deactivated, a character replaces selected text instead of surrounding it.
Specify the characters that should surround in the following STRING value of the registry:
HKCU \ Software \ Whole Tomato \ Visual Assist X \ <IDE spec> \ SurroundSelectionCharList = '/*{#(
Return to '/*{#( to restore the default behavior.
Note: Adding other characters to this list has NO effect on Surround Selection. Visual Assist ignores characters in the string that it does not recognize, and for which there is no built-in support.