s2member Pro Forms Generation Help Needed

[chelle]

Currently I am using express checkout with s2member and I have a php code snippet that goes into the button code as a piped delimiter for "custom field". I have s2member pro already and would really like to be able to use the ProForms so my customers can use coupons. Currently I am using PayPal express checkout, I am considering applying for PayPal Pro but not there yet

Where I am stuck is when I generate a form, it only gives me the shortcode, so I have no idea where to find the "real" form code to see where I could maybe place my php code (it goes as a piped delimiter for "custom field" in the PayPal button). I hard code all my buttons into page templates, so the shortcode makes it pretty much impossible to that as well.

So, basically my questions are:
1. How do I find the actual form code instead of a shortcode?
2. Is there a way to inject the php code I need to add somehow in the form?
3. Or, if the above is impossible, is there a way my customers could enter a coupon code using just the standard Express checkout PayPal buttons?

Thanks in advance for any help on this!