You have 3 main options if you want to remaster an ISO with additional applications:
1. Add them to the /tce/optional directory in the ISO image, and list them in the /tce/onboot.lst startup list. See
http://wiki.tinycorelinux.com/Integrating+Extensions for how to do this. This is relatively easy to do, and should have good bootup times, however you won't be able to remove the CD once the system is booted, and applications will load a little slower than with methods 2 and 3 because they have to be read off the CD when you start them.
2. Remaster the tinycore.gz and add the extensions to /opt/tce/optional directory and list them in the /opt/tce/onboot.lst startup list. See
http://wiki.tinycorelinux.com/Remastering for how to remaster the tinycore.gz. This will result in longer bootup times than method 1 and more memory usage, however the system will respond more quickly once booted (everything is in RAM), and you can remove the CD once the system is booted and use the drive for other things.
3. Remaster the tinycore.gz and extract the extensions directly in to the tinycore.gz. With this method, you follow the directions to remaster tinycore.gz on the wiki, and you then mount each extension and copy the contents of the extension in to the extracted tinycore.gz. You also need to run any startup scripts that go along with the applications (check /usr/local/tce.installed for the startup scripts). This has all the benefits of method #2 and will bootup more quickly than method #2.
You can either manually remaster, or the tc_remaster application automates any of the 3 methods. What error message are you getting with tc_remaster? You might want to check tc_remaster.log to see if it is logging what the problem is.
Brian