Thank you for posting in the e-z Cert forum. Certified documents are available from your local Chamber of Commerce. You can find your local office using this map:
You will need to complete a Formal Undertaking and Signature list before appling for documents but you can then use e-z Cert to apply online.
You mention EUROMED documents but I believe you may mean the EUR1, however if your goods are of US and Swiss origin the EUR1 is not applicable as the goods don't qualify.
Tunisia is part of the Arab League of countries so you should be using an Arab Certificate of Origin unless your customer/importer specifies otherwise.
You can combine both products on one invoice in order to apply for the Certificate of Origin.
If you require other non-certified documents, such as invoices, packing lists, standard shipping notes, dangerous goods notes etc. you may want to consider using e-z Consign. It's the sister product to e-z Cert. You can find out more and setup an account here:
Hope this information is of use.