*"Its rather painful to use the multi-replicate function to create something like this, so I was hoping to figure out how to either import spheres and turn them into metaspheres,"*

If you just want to change spheres to metaballs, just ungroup and select all the spheres and click the edit tab and with your mouse hold down the arrows and move the mouse along to the metaball icon and that should change all to meta's. However, metaballs are smaller than regular bryce spheres so you will have to re-arrange!

Hope this helps!