How to add files to a worflow created programmatically in perl

System

I've been trying to add a file to a workflow (and its tasks) that I create programmatically in perl.
I have tried 4 methods none of which work -

1. trying to set iw_file by using the workflow template object thus -
my $wft = TeamSite::WFtemplate->new(template => $template_file, file => $myfile, debug => 0);

2. trying to set iw_file by using the workflow template object thus -
$wft->{tag}{"iw_file"}{value} = $myfile;

3. trying to set iw_file by using the workflow object-
$new_wf->SetVariable("iw_file", $myfile);

OR finally

4. trying to set the attatched file directly to the task by using -
$new_task->AddFile($myfile);


Could anybody help me by suggesting which method I should be trying to make work? Or is there another way? And what form should my file information $myfile be in each of the above? String? Array? Hash? Reference to Array/Hash?

much thanks in advance

/Nick