Sorry Massimo, my regex foo isn't too good today. I'm not sure what connection string syntax you're expecting with your regex patch. I've tried the following connection strings but always get a 'User required' exception.
db = DAL('mssql://:@Server/database_name?Trusted_Conection=Yes')
db = DAL('mssql://@Server/database_name?Trusted_Conection=Yes')
~Brian
