I don't have any experience with this printer or Iomega device, so this will be generic advice.
From here: http://hplipopensource.com/hplip-web.../hp_setup.html
it seems to me that the HPLIP software will not directly support SMB shares. The screenshot clearly identifies network attached as direct attached or jet attached. So that appears to be out.
from here: http://hplipopensource.com/hplip-web.../cups/net.html
it explains with screenshots how to configure CUPS to use the device. However, it also appears dependant on the HPLIP drivers being installed because the first step is to locate the "unique" HP network string. You can try what they say and just use the IP of the IOmega device and see what happens. I doubt it will work, but worth a shot. If it returns the connection string then proceed with the installation.
Failing all that, my only other advice is to ensure that when you have CUPS auto install the SMB share, you try and modify the driver it is using to be the same as the locally install HPLIP driver per their instructions above. It may just be though that the HP printer depends on their software interpreting whatever information first.
Another idea, though you will have to hunt around to see if this is even possible, is to map the printer as an SMB share via cups, then share that printer out via an IP address from your machine, and then use that shared printer to send to HPLIP.