Unless you have a really expensive printer, it'll be easier to add a 2nd one. It's that, or you're going to have to redo your whole network scheme. Even then it can become quite dodgy, since you'd have to go completely static or risk DHCP fighting. It's not a very good idea to mix 2 networks like that.
I have seen people put together an old & small computer, add a 2nd NIC, and connect the printer directly to the computer, publicly shared on the 2 networks without having to bridge the networks. Again, it's just a lot of unnecessary headache and work that would be easier using a 2nd printer. If the printer is worth more than $4000, I would only then consider the latter method.