Bold arrows in xymatrix

If you try compiling this document with pdflatex

\documentclass{article}
\usepackage[all]{xypic}
\begin{document}
\xymatrix{A \ar@*{[|(3)]}[r] & B}
\end{document}

you receive the following warnings

<xymatrix 2x1

Xy-pic Warning: The linewidth 1.19994pt effect is not implemented
with the current driver. [notimpl:4].


Xy-pic Warning: The linewidth 1.19994pt effect is not implemented
with the current driver. [notimpl:4].


Xy-pic Warning: The linewidth 1.19994pt effect is not implemented
with the current driver. [notimpl:4].

44>

This means that the feature is not available with the current implementation of the xypdf driver (version 1.7)

This might be considered "bad LaTeX", but I've made some arrows bold by just putting in a few on top of each other.

\xymatrix {
    & A \ar[dl] \ar[dr] & \\
      B \ar[rr] \ar[rr] \ar[rr] \ar[rr] & & C}

gives

Sorry if that isn't the most helpful, but at least works as a temporary solution/last resort.