|If I'm understanding your question correctly, you want the network printer plugged in to both (separate) subnets. Is this correct?|
If that is what you're trying to do I'd research if you can put more than one network interface in your printer. This would be something to check with the manufacturer.
If you can't, then you won't be able to plug it in to two separate networks.
You might be able to use a router and enable the other subnet to reach the printer on it's subnet. However, that opens that subnet up to access from the other one.
The only other alternative I can think of would be if you have enterprise level managed switches and use VLAN's. If you can VLAN tag, then I'd put the printer in it's own separate VLAN (subnet) and give both other subnets access to that one. This would keep the two subnets segmented from each other, but still allow both access to the printer.
Having said all that....if you can't put two NIC's in the printer, the simplest thing would be to buy another network printer and plug it in to the other subnet.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.