Here's an example of read and write using a memory 'file' utilizing a scalar. Give it a try and see if Wx will be ok with it:
use warnings;
use strict;
my $read_memfile = <<'EOF';
one
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EOF
open my $mem_fh, '<', \$read_memfile;
print $_ while(<$mem_fh>);
close $mem_fh;
my $write_memfile;
open my $mem_wfh, '>', \$write_memfile;
print $mem_wfh "hello, world!\n";
close $mem_wfh;
open my $str_fh, '<', \$write_memfile;
print $_ while (<$str_fh>);
close $str_fh;
__END__
one
two
three
hello, world!