BCP, BULK INSERT and SSIS all have the ability to define the batch and commit sizes for data imports. If you are using one of these to import the data - then make sure you have set these values to a reasonable size.
If the database is in full recovery model - you can switch the recover model and potentially get a minimally logged operation (if you can meet the requirements). This could also be accomplished when in the simple recovery mode - but if you must stay in full recovery model then you will need to increase the frequency of your transaction log backups.