If you have enabled Debug Mode you should be able to add settings when you go to vBulletion Options. The best place to add your new option would be "General Settings".
So go to
vBulletin Option --> General Settings
Varname: switch_buttons_text
Title: Switch Buttons/Text
Description: Select Yes to use buttons. Choose No to use text.
Option Code: yesno
Data Validation Type: Boolean
In your template add
PHP Code:
<if condition="$vboptions[switch_buttons_text]">
Button goes here
<else />
text goes here
</if>