Hi Timboo,
Most filters screw into the bottom of the eyepeice as that one appears it would do as well.
don't know if your specificly after that IR filter but try Bintel, they have thier own UV/IR filters...
https://www.bintelshop.com.au/welcome.htm disregard the comming soon due April bit, appears they have not updated that page for awhile.
On my cam I can screw the filter into the cam as well for prime focus imaging.