Securing iPrint from the Outside

I am currently working with MS-ISAC to test my school network from the outside and my iPrint Appliance (4.2.8) sets off red flags during their security scans.  We have installed a wildcard SSL certificate to address one of their security concerns.  The biggest issue I am trying to address is how each printer provides the network path.  Is there a process to follow and secure my iPrint Appliance server while still allowing staff to print from home?  I am hoping that my only solution is not to allow the appliance to be accessed externally. 

Thanks in advance for any assistance!