These people always seem to have the latest link:
http://scully.cfa.harvard.edu/cgi-bin/returnprepeph.cgi?d=c&o=CK12S010


The following orbital elements are taken from MPC 85832:

    C/2012 S1 (ISON)
Epoch 2013 Nov. 4.0 TT = JDT 2456600.5
T 2013 Nov. 28.7762 TT                                  MPC
q   0.012448             (2000.0)            P               Q
z  -0.000154       Peri.  345.5631      +0.3151171      +0.5124965
 +/-0.000000       Node   295.6542      -0.7589391      -0.3692756
e   1.000002       Incl.   62.3911      -0.5698356      +0.7752308
From 5568 observations 2011 Sept. 30-2013 Nov. 14, mean residual 0".5.


;;IDL
tperi=anytim('2013/11/28')+86400.*.7762 - 67.183 & q=0.012448 & O=295.6542 & i=62.3911 & w=345.5631 & e=1
elements={tperi_ET_ccsds:anytim(anytim('2013/11/28')+86400.*.7762,/CCSDS),q:0.012448,e:1.0000020,O:295.6542,i:62.3911,w:345.5631}