44312 OSCommerce Mod

This is a two part project or I need two different things done. I am setting up an OSCommerce site for a doctor's office. They send out statements / invoices with varying amounts to different patients. What I need is a checkout process that will allow the patient / customer to input the amount due based on what their statement says. So, if a patient owes a $5 copay, they can input in a text field $5 and that will be what shows up under their checkout. Alternatively, if the owe $50, same thing, etc. I haven't been able to find anything on the OSCommerce forums besides questions. I've seen some work-arounds posted where they put the price as $1 then adjust the quantities, but this is NOT what I'm looking for. So, this has been posted on the OSC forums, but no responses and I haven't been able to find this on the OSC contributions section either. This could be used for churches / charitable orgs or any service company that has one "product" which is the amount due or a donation amount and needs to have this variable open for input from the customer of how much to pay. The second part of this, which I believe is one of the OSC contributions which I can install and get working is the "purchase without account". Listed on the OSC Contribution section under the top downloads (number 8 at time of writing) Whatever you come up with for the first part of this project should work without the patient / customer having to create an account. I.E. so they can just go through a simple checkout with the exact amount due. I'll be running this OSCommerce on a solaris box, but shouldn't affect the code at all I imagine.