In the past few centuries, Eris was really a southern object, whose position around A.D. 1800 was within the southern constellation of Indus. Eris then crossed through Indus and into northern Tucanae until about 1817, before moving into southern Grus, where it stayed until the early 1840s. From then Eris moved into Phoenix around 1874, then onto Sculptor until 1930, and thence into the equatorial constellation of Cetus the Whale. Eris will remain within this same constellation between 2006 and 2015, and does not it until 19th February 2037 !
Into our future, Eris will gradually move into the zodiac constellation of Pisces where it will stay until the 20th May 2060 AD. It will cross back and forth between Cetus and Pisces several times for a decade or so, where it will move into the zodiacal constellation of Aries on 10 April 2065. Next, Eris will leave Aries and become a northern object within the non-zodiacal constellation of Perseus sometime in June 2127. After 2175 AD, Eris will become a far northern object, residing in Camelopardalis until the 23rd Century, when the declination reaches its maximum of around +64°N in 2200 AD.
It should be importantly noted that these positions and times remain tentative because the lack of historical positional data. So far the oldest identified position is from one plate made on 20th January 1963, meaning that we have orbital information based on just forty-five years (2008) or just 8% of the entire orbit.
All sky positions given below should be sufficiently accurate for most amateur purposes. However, beyond the next few decades, future ephemerides may change slightly with adjustments to the orbital elements. Perhaps the greatest difficulties are assessing the many perturbations caused by the gravitational pull of the other planets and planetary bodies in the Solar System. Better knowledge of these effects will likely be determined in the coming decades.
Telescopically, distant Eris only appears as a very faint star but remains invisible to all amateur telescopes. It is possible to record the faint body by amateur deep CCD images, though its detection likely requires a lengthy exposure of at least 20cm in aperture.