yes it is possible. with only a few workarounds, you can definitely use your nook color as an awesome comic book reader.
1. if you have .cbr or .cbz files at your disposal, what you need to do first is to convert it into a rar or zip file. how? just rename the file and replace the .cbr or .cbz file extension with .rar or .zip.
2. after doing that, unzip or unrar your file.
3. find an appropriate program to create a single pdf file from your series of jpg comic pages. adobe acrobat 10 works for me. (though there may be other reliable programs available online)
4. after you've created your pdf comics file, just transfer it to your device and voila! you can now view your comics files to your nook color. :D