You can install TWO sets of drivers for your shared printer, one x64 and a second x86, hosted by your x64 machine.
When the other x86 network machines go through their "add printer" dialog and you navigate them to the shared printer hosted by your x64 machine, the x64 machine will send the x86 second driver to the x86 machine.
Right-click on your printer object on the x64 machine, select "printer properties" and select the "sharing" tab. Then push the "additional drivers" button to begin the wizard dialog to begin the install for the x86 drivers on your x64 machine where you already have x64 drivers installed.
With the x64 driver already currently installed (so its checkbox is already checked), check the currently unchecked x86 box and push the OK button to continue on. You will then point to the expanded folder in which the x86 driver files have been placed (i.e. on of the sub-folders contains the needed INF files for the x86 version of the drivers). Presumably you've downloaded the x86 driver installation file from Brother and either (1) expanded it, say with WINRAR, or (2) run it as if you were going to install it but instead you CANCEL after it self-expands. Once the driver installer file has been expanded, the needed INF files are now present in some sub-folder and will be automatically found by this "additional driver" process.
When this whole process is complete, you will now have TWO drivers installed on the x64 machine. The x64 drivers will be used when printing directly from the x64 machine, and the second x86 drivers will be delivered to any x86 machine during the "add printer" dialog from that machine t point to the shared printer hosted by your x64 machine.
Now when you print from an x86 machine, the x86 driver on that machine will be used but the rendering of the printed output will be on the x64 machine (to which the printer is connected) which really is doing the "hosting" of the printer available for shared printing needs by ALL computers on your network, both x64 and x86 thanks to installing both drivers on the x64 host machine.