Looks like a Perl answer may not help you at this point, but since it's in the Perl forum...
my $var = "(02:25:26) user: message";
$var =~ /\((\d+):(\d+):(\d+)\) (.+):(.*)/;
you put paranthesis around the parts of the expression you're trying to capture. Now we also have to escape literal paranthesis.
They get stored in automatic variables $1, $2, $3.... from left to right
so
$1 = 02
$2 = 25
$3 = 26
$4 = user
$5 = message