Hi Antonio,
using a companion file (*.csvt) so to specify the intended data
type for each column being imported from a CSV file is an
additional extra feature specifically introduced by GDAL.
it's not part of the most universal CSV format specifications as
generally intended by the many other sw packages implementing
some kind of CSV parser, and AFAIK only GDAL itself is able to
support *.csvt files.
GDAL supports a very nice and effective SpatiaLite driver, so
if you absolutely need to use a *.csvt companion file you
could easily use GDAL for loading your CSV data into a
SpatiaLite DB-file.
bye Sandro