This seems to work. Put the first block of code at the beginning of your sidebar:

<?php
// Trick the sidebar into thinking we're on Blog All:
$saved_blog = $blog;
$blog = 1;      // Blog All now
?>

And this next one at the end of your sidebar:

<?php
// Restore after dirty trick:
$blog = $saved_blog;
?>

It's exactly what i needed!

Thank you a lot! :)

Lucas