Yes you can use the Brother MFC-490CW without the CD disc, assuming a supported OS is running on the computer. You will need to download the software from the support site: https://support.brother.com/g/b/downloadtop.aspx?c=us&lang=en&prod=mfc490cw_all
. Select your OS and click the OK. To use all of the features of the all-in-one, download the full driver & software package. If you only get the Add a Printer Wizard, the scan functions won't work.
Note: make sure to install the software before connecting the printer to the computer if you use a USB cable. If Windows sees the printer first, it will download a generic MS printer driver and no scan functions will be available. You would have to remove the generic driver and disconnect the USB cord before installing the correct drivers. You can find the manuals for the MFC-490CW by clicking on the Manuals button on the above page. Make sure to start scanning from the computer and then set the Brother software following the directions in the documentation to have the printer "see and respond" to the buttons.
The missing CD had some third-party software that is not available from Brother's Download site. These aren't required to use the all-in-one.
I hope this helps.