( For the reason I explained here, this node doesn't help the OP. This one does. )

Would the following do the trick?

# Info extracted from
#    <script onInit='use strict; my $x; my $y;'
#            onAwaken='print ++$x'
#            onAwaken='print ++$y'/>
#
my $onInit   = 'use strict; my $x; my $y;';
my $onAwaken = 'print ++$x';
my $onSleep  = 'print ++$y';

# Compile code
my $code = "package Sandbox;"
$code .= "$onInit;";
$code .= "sub onAwaken { $onAwaken }";
$code .= "sub onSleep { $onSleep }";
eval $code;

# Dispatch an event
Sandbox->onAwaken() if Sandbox->can('onAwaken');
[download]

The above can easily be expanded to handle multiple documents by generating incremental package names.