The short answer is yes, yes you can.
Because bone conduction bypasses the ear entirely and directly stimulates the ossicles (which is the scientific name for the tiny bones that reside in your inner ear, as well as the rationale behind comic book hero Daredevil's athletic prowess), it is entirely possible to stick your ear plugs in and still listen to your 'Bonephones'.
In some respects, it's actually preferable. Y'see Nick, using headphones is fine and dandy, until you have to turn the volume all the way up in order to drown out noisy children, busy traffic and/or people shouting into their phones all around you. After that, if you increase the volume to too great a degree, you can expose your ears to sounds that can actually permanently damage your hearing.
Bone conduction, however, carries much less of a risk, because it does not effect the parts of the ear most at risk from loud noises.
Hearing is a process that actually has several stages. At first, your ear picks up sound waves, the sound waves pass into your middle ear (specifically, your auditory canal) before hitting the eardrum. The eardrum then vibrates, passing the sound down to the aforementioned ossicles ('aforementioned ossicles' is a lovely phrase, don't you think?) From there, the ossicles transmit the sound to the cochlea, which is a fluid-filled structure that encodes the sound information in order for our brain to decode it (this is not unlike the way a wireless mouse works, actually).
Yup, the inner ear is a wacky world.
Essentially, bone conduction technology rattles the ossicles in the same way that they'd rattle in your inner ear, it just, to turn a phrase my father is particularly fond of 'cuts out the middle man'. It really is an interesting invention.
So, as you see, there is no way a pair of earplugs pose any problem at all to your enjoying music or audio content on your Bonephones. I hope this helps. You'll likely find this method especially useful if you happen to find yourself on a long plane journey and seated next to a disgruntled infant.
I'm actually fairly certain that bone conduction technology was invented during a similar scenario.
Have fun, Nick.