Overiding the Curse Mark
I've come up with an idea to cure and overide the curse mark.
There are two types of chakra; yin and yang (yin chakra is evil chakra and yang chakra is good chakra). In living beings there are equal amounts of these chakras. The curse mark works by giving you extra yin chakra, and off-setting the balance of good and evil inside yourself.
Now the curse mark is a three pronged seal of yin chakra, so a four symbol seal would negate the effects of the curse mark, and allow for some leway as well.
My idea is to use two four symbol seals on the curse mark, negating the yin chakra, and actually converting it into yang chakra. This would allow the person with the curse mark to gain access to it, but in a good way; getting good chakra (yang) instead of bad chakra (yin).
If anyone would like to be subject to a test of this, let me know because it could well increase your power in a good way.