The printer settings used for printing depends on the printing application.
Printers have several settings ( for example an HP printer can have 600x600 and 1200x1200 DPI for resolution), therefore the printing application is the one who decides which settings to use.
The only way to 'force' a setting is to limit the printer driver to use only that particular settings, and do not accept any other setting. In your case this would involve a custom version of the printer driver which would print only the Tiff Group 3 1D file format.
We recommend two things:
1. Create your printer setup in that way that it installs the Black Ice printer using the Tiff Group 3 1D file format as default. This way any application which tries to use the printer's default settings will receive a devmode with the Tiff Group 3 1D file format. JPEG is the default file format for the color driver.
2. If you install the printer driver the above described way, and as you say do not enable your user to change the file format, they cannot produce a document with a different devmode in it. However, if you want to be 100% sure that the printing produces only TIFF, even if the document has a different devmode saved in it, you can use the BLACKICE_MESSAGE_DEVMODE message sent by the printer driver at every start page. Your application should capture this message. The current devmode comes with the message, your application can check the file format and change it if it is necessary.
For more details about this option please check the Pipe Message Capture Sample.