Semantic XHTML?

I have the editor configured to only permit paste as text. However, if the user pastes in the following text:

Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Phasellus sed erat quis nisi dictum nonummy.

Cras vehicula. Praesent elementum
Nisi quis dapibus aliquet nortor nisl tincidunt pede, ut faucibus massa purus vel libero.

Quisque leo erat, imperdiet ut, luctus nec, congue id, diam. Mauris ornare fringilla libero. Donec ullamcorpe.

It pastes in with the following XHTML:

Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Phasellus sed erat quis nisi dictum nonummy.<br /><br />Cras vehicula. Praesent elementum<br />Nisi quis dapibus aliquet nortor nisl tincidunt pede, ut faucibus massa purus vel libero.<br /><br />Quisque leo erat, imperdiet ut, luctus nec, congue id, diam. Mauris ornare fringilla libero. Donec ullamcorpe.

Does anyone know how to make it paste in like this:

<p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Phasellus sed erat quis nisi dictum nonummy.< /p>
<p>Cras vehicula. Praesent elementum<br />Nisi quis dapibus aliquet nortor nisl tincidunt pede, ut faucibus massa purus vel libero.</p>
<p>Quisque leo erat, imperdiet ut, luctus nec, congue id, diam. Mauris ornare fringilla libero. Donec ullamcorpe.</p>

Thanks,
Chris