Custom 'Add to Cart' link (no product)

[Cedwyn]

Is it possible to build a custom add to cart link without an existing product?

For example, when using the 3rd party check-out site (http://ww11.aitsafe.com/)  you can create a link as follows:
http://ww11.aitsafe.com/cf/add.cfm?userid=12345&%20product=Test%20Product&price=20&units=0&tax=13;return=www.xxx.yyy
uid is replaced, so this won't work if you try it, but what will happen with a correct id is it adds the 'Test Product' to the 3rd party shopping cart with a price of $20 and 13% tax.

I have converted a site to use vm2 and the vm2 shopping cart, so I don't need aitsafe anymore, but there are a few services that my client sells which I would prefer to use this method if possible (rather than add the services as products).  I am php programmer and have written several joomla modules/plugins, so if anyone can give me some direction on how I can do this in VM would be much appreciated!

Thanks,
Cedwyn