Solved it manually. Mine was running 4 hours ahead, so I had to subtract 14400 seconds (4 hours x 60 minutes x 60 seconds).
I don't actually store items differently in the database, I just have it show correctly on my site.
In the file wp-content/plugins/lifestream/themes/default/main.inc.php
Line 5, change to:
$today = date('m d Y', time()-14400);
Line 6, add 14400 (or whatever your number is) to the number at the end, so it looks something like this:
$yesterday = date('m d Y', time()-100800);
After line 18, insert this new line:
$timestamp = $timestamp - 14400;
In line 42, look for:
and have it subtract your 14400 from the end, so it looks like this:
That should do it!