Editing BibTeX stylefile from Biometrics Journal to accommodate their requirements

For submitting a paper, the references need to be in the following format:

References in the text should be ordered by author's surname and publication date. In publications by three authors, all are listed the first time, and et al. used subsequently. For four or more authors, et al. is used throughout. In the list of references at the end of the paper, authors should be listed alphabetically by last name. For references with more than six (6) authors, only the first six (6) authors should be listed, followed by "et al." Journal titles should be complete and not abbreviated. Careful attention should be given to the format used in recent issues.

Source: http://ift.tt/1rSGPnm

The journal provides a documentclass and a BibTeX stylefile that can be downloaded from http://ift.tt/12ky9Am

However, the stylefile does not do the following things:

• In publications by three authors, all are listed the first time, and et al. used subsequently.


• For references with more than six (6) authors, only the first six (6) authors should be listed, followed by "et al."

From a different post, I know that the second point can be done by rewriting the following function from the provided .bst file (see http://ift.tt/1rSGOQq), however, I don't know what exactly I have to change in this function.

FUNCTION {format.names}
{ 's :=
  #1 'nameptr :=
  s num.names$ 'numnames :=
  numnames 'namesleft :=
    { namesleft #0 > }
    { s nameptr "{vv~}{ll}{, jj}{, f.}" format.name$ 't :=   
      nameptr #1 >
        { namesleft #1 >
            { ", " * t * }
            { numnames #2 >
                    { "," * }
                    'skip$
              if$
              t "others" =
                { " et~al." * }
                { " and " * t * }
              if$
            }
          if$
        }
        't
      if$
      nameptr #1 + 'nameptr :=
      namesleft #1 - 'namesleft :=
    }
  while$
}

Here is a minimal working example of a .tex file that illustrates the two issues mentioned above (you need the files from http://ift.tt/12ky9Am to compile the following code):

\documentclass[usenatbib, referee]{biom}
\usepackage{filecontents}
\title[Title]{Title}

\author{Author$^{*}$\email{email@address.com} \\
       Institute of the Author, Postal Code, State
       }

\begin{filecontents}{report.bib}
@Article{hatzis2011genomic,
  Title                    = {{A Genomic Predictor of Response and Survival Following Taxane-anthracycline Chemotherapy for Invasive Breast Cancer}},
  Author                   = {Hatzis, Christos and Pusztai, Lajos and Valero, Vicente and Booser, Daniel J and Esserman, Laura and Lluch, Ana and Vidaurre, Tatiana and Holmes, Frankie and Souchon, Eduardo and Wang, Hongkun and others},
  Journal                  = {Journal of the American Medical Association},
  Year                     = {2011},
  Pages                    = {1873--1881},
  Volume                   = {305},
}

@Article{Pepe2008,
  Title                    = {{Comments on 'Evaluating the Added Predictive Ability of a New Marker: From Area Under the ROC Curve to Reclassification and Beyond' by M. J. Pencina et al., Statistics in Medicine (DOI: 10.1002/sim.2929)}},
  Author                   = {Pepe, M S and Feng, Z and Gu, J W},
  Journal                  = {Statistics in Medicine},
  Year                     = {2008},
  Pages                    = {173--181},
  Volume                   = {27},
}
\end{filecontents}

\begin{document}

\begin{abstract}
Abstact
\end{abstract}

\begin{keywords}
Keywords
\end{keywords}

\maketitle
Two examples that do not work with the provided .bst files:
\begin{itemize}
\item In the reference list of \citep{hatzis2011genomic}, the first 10 authors are listed and not the first 6 as required by the journal.
\item The citation of \citep{Pepe2008} shows only `Pepe et al.', however, the journal requires that `publications by three authors, all are listed the first time, and et al. used subsequently.'
\end{itemize}

\bibliographystyle{biom} \bibliography{report}

\end{document}

This yields the following pdf:

Could someone please help? Thanks in advance.