Sadly, it's not possible to achieve in BF2 engine.
It's one of the few things BF1942 actually does better (along with moveable ships, tank engine disabling and ammo resupply system - and some more obscure things that are possible to achieve such as 3rd person vehicle entering animations).
There is however a way for the devs to skip attaching bayonet animation - simply make some kits have them permanently attached! I suggested it multiple times for maps that feature "duplicate" kits (a version with and without grenades) such as Tunis and Ramelle. But my suggestion unfortunately didn't impress any dev enough to bother implementing it.