Let's separate the problem into parts.
1. Are you talking about Avira's NTFS4DOS? If that's the case, I don't think the official download has any instructions related to UBCD. Additionally, it is a tool that is no longer supported by Avira and it has not been updated for several years, currently for personal use only; so if there is any kind of problem or incompatibility with NTFS4DOS, specially in volumes formatted and used under Windows 6.x (Vista / Seven), there is no way to be aware of it nor solve it. There are other NTFS drivers for DOS, JFYI.
2. The method to add NTFS4DOS would depend on what exactly you would want to add. You could add the bootable floppy image, or the bootable CD image, or you could edit the UBCD FreeDOS image so to add the driver there. For each case, the method slightly differs, and you should look at the info in the several sections of the main UBCD website (faqs, customizations, tutorials...) at http://www.ultimatebootcd.com
to find out how to do it with the current
version of UBCD.
The current UBCD v5.1.1 has an iso.gz image, and inside it you could find DOS apps, including also the UBCD FreeDOS floppy. The instructions in the above mentioned faqs, tutorials, etc. were updated accordingly.
3. UBCD includes a version of PartedMagic (although, not the latest one, but it can also be updated separately). Booting into UBCD -> PMagic, you should also have access to NTFS volumes. Depending on your hardware, you could even update UBCD with the latest PMagic, or download PMagic and use it independently of UBCD.
4. If you "must" use NTFS4DOS, look at the already indicated sections to find the relevant info. If you need "some" NTFS driver for DOS (for example, if the hardware can't support anything else other than DOS), search also for alternative drivers, in addition to the "faqs, customization, tutorial..." sections. If you are not really interested in the DOS part, but rather in the access to some NTFS volume / partition, then evaluate the PMagic option. If your final "real" goal has more to do with, for example, access to some NTFS volume so to recover files, then the approach can be much different, with less "customizations" steps and more directly into work.
If I wasn't clear enough, please provide more specific info and I'll try to clarify.