--
There is also an undocumented function FeynCalcToLaTex
in HighEnergyPhysics/general, but it is broken under
Mathematica 5.2 (should work with 5.0 or so).
I think you (or somebody else on this forum with time?)
could fix it easily. The idea was to functionalize
TeX-creation of (larger) expressions, using TexSave and
subsequent string replacements.
I wrote this for LaTeX-generation of the FeynCalc book
(when working on it with Frederik two years ago ...).
I'll copy the code below.
Rolf 
(* :Title: FeynCalcToLaTeX *)
(* :Author: Rolf Mertig *)
(* ------------------------------------------------------------------------ *)
(* :History: useful for documentation, but probably also otherwise *)
(* ------------------------------------------------------------------------ *)
(* ------------------------------------------------------------------------ *)
BeginPackage["HighEnergyPhysics`general`FeynCalcToLaTeX`",
             "HighEnergyPhysics`FeynCalc`"];
FeynCalcToLaTeX::usage="FeynCalcToLaTeX[expr] generates LaTeX with line-breaking
for expr.
FeynCalcToLaTeX[expr, 500] generates LaTeX for expr with 500 being the Window width
 setting for the Mathematica frontend. Increasing its value will generate less
line breaks.";
F2L::usage="F2L is the same as FeynCalcToLaTeX.";
Begin["`Private`"];
MakeContext[StringChomp];
F2L = FeynCalcToLaTeX;
FeynCalcToLaTeX[expr_, width_:500] := If[!$Notebooks,
   Needs["JLink`"];
   JLink`InstallJava[];
   JLink`UseFrontEnd[f2tex[expr, width]],
   f2tex[expr,width]
];
(* this is of course heuristics; should change to java.util.regexp or so ... *)
f2tex[expr_, width_:500] := Module[{r, n, w,y,z},
   r = Cell[BoxData[FormBox[(MakeBoxes[#1, TraditionalForm] & )[expr], TraditionalForm]],
      "Output"]; n = NotebookPut[Notebook[{r}, WindowSize -> {width, Inherited},
       Visible -> False]]; o = StringJoin[$TemporaryPrefix, ToString[Random[Integer, 10^8]],
      "fc2latex.tex"]; TeXSave[o, n]; t = Import[o, "Text"];
    w = StringDrop[StringChomp[ StringReplace[StringDrop[t,
         StringPosition[t, "dispSFoutmath"][[1,1]] + 13],
          {"\\end{document}" -> "",
         "\\MathBegin{MathArray}{l}"->"",
         "\\MathBegin{MathArray}[p]{l}"->"",
         "\\MathEnd{MathArray}"->"",
         "\\NoBreak" -> ""}
         ]], -2]; DeleteFile[o]; NotebookClose[n];
    y=StringChomp[StringReplace[StringJoin@@(Characters[
        w]//.{in___,"\\",_,"s","p","a","c","e","{",___,"}",
          fi___}\[RuleDelayed]
        {in,fi}) ,"\\noalign{}"->""]];
    z = StringReplace[FixedPoint[StringReplace[#, "  "->" "]&,y],"\n \n"->"\n"];
    z=StringReplace[StringReplace[z,"\\\\\n"->"\n\\\\\n"],"\n\n"->""];
    z = StringReplace[z,"\n\\\\ (\n"-> "\n\\\\ \n( "];
    If[StringMatchQ[z,"*\\\\"], z=StringDrop[z,-2]];
    If[StringLength[z]>1,
       If[StringTake[z,1]==="{" && StringTake[z,-1]==="}",
           z = StringDrop[StringDrop[z, 1], -1]]
      ];
    (*z = "$\n"<>z<>"\n$";*)
    (*not always useful, comment it out for now
     CellPrint[Cell[z, "Program"]]
    *);z]
End[]; EndPackage[];
(* ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ *)