I guess you need some value proposition. Remember that most companies are in the business of making money, and it needs to be the case that you can give more than it takes to employ you in terms of usage of staff time, resources, training, office space. Here are a few ways you can do this:

- Offer to help with more general systems development/support as well as the security element. You might have to spend a signficant percentage of your time acting as a cheap coding monkey in order to get exposure to the stuff of relevance to you.

- Offer to train other staff free or charge, or provide audit or documentation for systems.

- Highlight the risks of security problems in terms of real monetary costs to an organisation who don't invest in security.

- Sell yourself as an independant and pro-active potential employee who won't be a drain on resources.

- Be flexible in the work and projects that you can offer. Remember that you will only be hired for the work experience if you can fill a valid required business objective.

- Cast your net wide, and speak to people on the ground in an organisation. Contacting a small group of companies via HR departments is a guaranteed way for your e-mails to end up in a black hole.

- Get on the phone or right physical letters. They're emotionally harder to discard or ignore than an e-mail.

- Remember to contact non-obvious choices such as schools, charities, NGO's, open source projects?

- Above all, be enthusiasitc and state your willingness to learn!