How about using do like this? Create your MyInit.pl like so:

use v5.18;

BEGIN {
    use List::MoreUtils qw| any               |;
    use Scalar::Util    qw| looks_like_number |;
    use Fatal           qw| open              |;
}

sub mySub {
    say "This is mySub, foo!";
}
[download]

Then you can write your script like so:

#!/usr/bin/perl
use v5.18;

BEGIN {
    do 'MyInit.pl';
}

mySub();

my @array = ( 'one', 'two', 'three' );
if( any {$_ eq 'two'} @array ) {
    say 'So far so good...';
}

if( looks_like_number( "five" ) ) {
    say 'Hmm...';
}
else {
    say 'Perl can\'t read.';
}

open( my $dne, '<', 'nonexistentfile.txt' );
die 'Failed to import autodie';
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Which seems to work like so:

peter@hermes:~/src/Perl/test> perl myscript.pl 
This is mySub, foo!
So far so good...
Perl can't read.
Can't open(GLOB(0x9cc7d8), <, nonexistentfile.txt): No such file or di
+rectory at (eval 3) line 4.
        main::__ANON__('GLOB(0x9cc7d8)', '<', 'nonexistentfile.txt') c
+alled at myscript.pl line 22
[download]

The trick with autodie was that its import just gotos the import function from Fatal. So I just cut out the middleman.