# Semi-colon after first author, comma after multiple authors in bibliography

I'm working on a bst file for a journal with very peculiar formatting instructions for the references section. Namely, the references section needs to do the following.

1. Feature a semi-colon after the first author in a citation including at least three co-authors.
2. Have a comma separating second author from third author and all the way to the penultimate author in a citation with at least four authors.
3. Have an ampersand separate the penultimate author from the final author.

Consider the following image:

For the fourth and fifth citations in that list, how do I replace the semi-colon with a comma for the citations after the first author (i.e. starting with the second author)?

The bst file I'm creating is derivative of newapa.bst, though I hacked at it to do multiple things. Basically, everything else in the bst file is to specification, including grepping out middle initials (a trick I learned from asking another question on this same site) and de-capitalizing most of the title in the @ARTICLE class. I just need it to use commas in lieu of semi-colons to separate authors in articles and books (and whatever else) with more than three authors (up until the penultimate and final author). I hope that makes sense.

Since I admit this is a complicated bst file I created, here's a pastebin link to the .bst file for a week: http://pastebin.com/HUEiSCtS

Here's an example tex file with which to work:

\documentclass[11pt]{article}
\usepackage[left=1in,top=1in,right=1in,bottom=1in]{geometry}
\usepackage[compress]{natbib}
\setcitestyle{aysep={},citesep={,}}
\usepackage{titling}
\newcommand{\subtitle}[1]{%
\posttitle{%
\par\end{center}
\begin{center}\large#1\end{center}
\vskip0.5em}%
}

\title{*.bst Example}
\subtitle{Some Random Citations for Demonstration}
\author{Guy Posting Things on the Internet}

\begin{document}

\maketitle

\section{Introduction}

Here are some citations to some really cool research \citep{firstcite,secondcite,thirdcite,fourthcite,fifthcite}.

\bibliographystyle{examplebst}
\bibliography{example}

\end{document}


Here's a list of sample citations for rendering the bibliography in question: http://pastebin.com/PbnFygZ5

I admit I'm no BiBTeX expert and a lot of what I learned is trial and error. I think the issue here is in format.rem.names in my bst file, but wouldn't know the scope of what needs to be done.

Truly any help would be appreciated. Thanks.

-