A small bead of silicone (the GE SiliconeII has a screw on cap) will help hold those things in place, give you an airtight seal and the driver is still easily removed. Another thing you can do it use silicone on the T thingies to keep them stuck to the inside of the cabinet and put a bit of vasoline on the bolt so the silicone won't stick to it.
I am guessing you are removing the drivers, getting the thingies set in place so they won't come loose, then putting your drivers back in.
Are the thingies spring loaded dry wall anchors? If so the silicone and vasolined bolts will definatly work. Just leave them set over night, get your drivers back in and sealed with a bead under the edge of the basket and let that sit over night.
Another thing you can do if the baskets on the woofers are stamped and not cast is to get rolls of that non drying caulk and run a line down the basket ribs, around the outside and where the magnet is attached. That will absorb any ringing or vibrations you might get in the baskets and keep it from having your cabinet resonate. This is especially important if you put down a thick bead between the rim of the basket and the cabinet becaust that tends to isolate the driver from the cabinet. While this will cut down on cabinet resonance, the basket has nowhere to pass the resonance it creates and must be damped. This is cheap and easy to do.
And if you are going to be in there try and find out the values of any capacitors in the crossovers so that you can look at replacing them later.
The next things to think about on improving the sound of your speakers is better crossover componants and new wiring starting with quality binding posts.