Hi,
I have a similar 2.5 " blast gate (from Woodcraft I think). On mine the Festool hose fits into it perfectly (as well as a regular shop vac hose). And it has the same OD as the Festool 'Y'. A very neat adapter could be made from the end of an extra shop vac hose or by cutting the end off a regular shop vac cleaning tube (wand). You only need a short piece about 2" long to connect them.
Then just a short piece of wire screwed , taped , or inserted with the fitting to jump the anti-static over the blast gate.
Seth