To Enable Exalead logging in the AppSetting.xml file, make sure that the Db.LogEvent key looks like:

<add key="Db.LogEvents" value="Errors,Main,Exalead" />

After you perform a search, in the log there should appear entries such as:

/*

  Exalead Search

  2012-12-24T10:19:37.362+02:00

-Search Query: test AND id==190529

-Sort Name: 

-Start index: 0

-Is mixed SQL search: False

*/