Almut's solution is good, but not scalable. If you use a hash, you can easily add more dates in the future.
my %DATES = (
"7/Jun/2010:23:02:10 " => "2010061802:00:14",
"7/Zog/2100:12:63:13 " => "2010060608:39:11",
"my birthday" => "1974012618:12:10",
#simply add all the other dates to this hash!
);
sub convert {
return $DATES{$_[0]}
}