How do I blacklist a package?

[Stefan Monnier <monnier@iro.umontreal.ca>]

APT keeps wanting to install `sse2-support` on my dear Thinkpad X30, but
that machine's CPU does not support SSE2, so the package's installation
always fails.

How can I tell APT that it shouldn't *try* to install `sse2-support`?

I tried to put a "hold" on the package with

    echo "sse2-support" | dpkg --set-selections

but it apparently only works to pin an *installed* package to it current
version, whereas I'd need it to "hold" the "uninstalled" status.

Any hint?


        Stefan