Not sure if this link will help, but has updated orbital elements for different programs:
http://www.minorplanetcenter.org/iau...ftwareEls.html
As for the JPL orbit it appears to be similiar to the original orbit published in
MPEC 2010-X101 on December 12. However, the latest orbit on
MPEC 2010-Y24 is based on 12 days of observation. I believe the perihelion distance and general orbit is pretty close to correct in Y24, however I believe the Perihelion date may change a couple of days.
For stellarium it seems that
q = orbit_PericenterDistance
T = orbit_TimeAtPericenter (but you have to convert to Julian Date).
So the try these:
[Elenin_C2010_X1]
# Data taken from JPL/HORIZONS
# correct for the specified time frame:
# Start Time : A.D. 2010-Dec-29 00:00:00.0000 CT
# Stop Time : A.D. 2010-Dec-29 00:00:00.0000 CT
name = Comet Elenin (C/2010 X1)
parent = Sun
coord_func = comet_orbit
radius = 10
oblateness = 0.0
albedo = 1
lighting = true
halo = true
color = 1.0,1.0,1.0
tex_halo = star16x16.png
tex_map = nomap.png
lighting = false
orbit_Epoch = 2455808.50000
orbit_TimeAtPericenter = 2455808.92662
orbit_PericenterDistance = 0.4420298
orbit_Eccentricity = 1.000000
orbit_ArgOfPericenter = 345.23890
orbit_AscendingNode = 323.24604
orbit_Inclination = 1.84963
Terry