Use isofix (https://github.com/arthabus/DreamcastCdiTool/raw/master/DreamcastCdiTool/isofix.exe) to convert the data track to an extractable ISO. To determine which is the data track, refer to the Redump info page for the rip. For example, here's a disc with its data track as 13: http://redump.org/disc/66404/.
When prompted for LBA, refer to the Redump page again and note the start of session 2 (e.g., 190412).
The fixed.iso file generated by isofix can be extracted by any number of tools, such as 7-Zip or IsoBuster.
Once the data track is extracted, your next step is to convert the disc image's CDDA tracks to WAV using bin2wav (https://github.com/saramibreak/bin2wav). This utility is pointed directly at a Redump disc image's CUE file and will output all audio tracks as WAV files.
Next, fire up BootDreams (https://github.com/TItanGuy99/BootDreams), being sure to place all the newly converted WAV files into the cdda folder if your source disc image uses CDDA. Then, tell BootDreams where your extracted data track resides, after which you can generate an Alcohol 120% image if the source disc image is using CDDA. If CDDA is unnecessary, choose to generate a DiscJuggler CDI.
If your source disc image had CDDA and thus you now have an Alcohol 120% MDF/MDS, use an application like Daemon Tools to mount it to a virtual drive. From there, DiscJuggler can be used to rip that virtual disc to a CDI.
EDIT: I'd like to clarify that I am NOT sharing this information in order to condone the pirating of indie titles that are currently available for sale and thus still directly profiting hard-working developers. However, I know many of us no longer have optical drives in our home computers, thus preventing us from ripping our own legally purchased Dreamcast indie games.
