Hi Shiv,
Are u importing thru excel interface or programmatically? Thru Excel
if u use
Data-Import External Data-Import Data and then select the CSV file
and follow the steps, u can modify the data type of the desired column
from MDY to Text.

If programmatically, then to the opentext method you can give in
FieldInfo, array specifying the data types of columns.

Hope this helps.
Regards,
Mahesh