I think this would work...

my $init = eval <<EOI;
sub {
  $INIT_CODE;

  my \$sub = eval q(sub { $AWAKEN_CODE });
  die "bad onAwaken: \$@" if \$@;
  \$sub;
}
EOI
die "bad onInit: $@" if $@;
my $awaken = $init->();

...

# and later onAwaken...
$awaken->();
[download]

though you would probably want to improve the quoting for the inner eval argument.

update: or if several attributes as onAwaken can exist:

my $init = eval <<EOI;
sub {
  $INIT_CODE;

  my \$sub = eval 'sub { \$_[1] }';
  die "bad \$_[0] code: \$@" if \$@;
  \$sub;
}
EOI
die "bad onInit: $@" if $@;

my $awaken = $init->(onAwaken =>$AWAKEN_CODE);
my $foo = $init->(onFoo => $FOO_CODE);
...

# and later onAwaken...
$awaken->();

# and onFoo;
$foo->();
[download]