You're writing a REST service which in turn accesses a SOAP service; is that correct? if so, it's most certainly still a REST service. Why wouldn't it be? And where do you see problems implementing it?
Ah...... horse of a different color! So you're writing a translation layer to create a REST API that leverages an existing SOAP service?
As Tim asked, why do you think there's a feasibility issue? Although I'd likely say that unless the existing processes are highly complicated, it'd likely be easier and cleaner to recreate the services from scratch as to perform a lot of translation code.