Not directly.
The way the plugin works is that it creates an HTML form that interacts with PHP code that compiles the information obtained from the form. The PHP formats everything for the gateway and creates an MD-5 security hash based on information about the transaction and the Transaction Key. The PHP then submits everything to the gateway.
If you know how to edit HTML, in Chrome you can Inspect (Ctrl+Shift+I) the form and copy it to your favorite code editor. You can then change or modify the form as you see fit, including turning the inputs into dropdowns. Then, you can copy and paste your newly created form into the body of a page using the Text mode (not Visual).
If you’re not comfortable editing HTML, you can contact me directly.