This would work out of the box with the QuickLaTeXQuickLaTeX plugin (which I believe is only available for self-hosted WP blogs so I'm not sure this applies to the OP). The input
[latex][+preamble]\usepackage{amsmath}[/preamble]
\begin{align*}
\int \frac{1}{(2x^{2}+4x-2)^{-\frac{3}{2}}} \textrm{d}x
&= \frac{\sqrt{2}}{8} \int\frac{\sec{t} \cdot \tan{t}}{\tan^{3}{t}} \textrm{d}t \\
&= \frac{\sqrt{2}}{8} \int\frac{\cos{t}}{\sin^{2}{t}} \textrm{d}t
\end{align*}[/latex]
gives me on my blog