To have the BCC Snow accumulate you'll need a surface on which the snow can stick to, which in this case is the 3D Text. You don't necessarily need to apply the filter to this layer but it has to exist in the comp. Pre-comp the 3D Text layer to ensure that it passes alpha information to the BCC Snow filter.
So ... once you have an instance of the BCC Snow filter in the comp, twirl down the BCC Snow Interaction group. Then select the precomped 3D Text layer in the Stick to Layer pop-up in the filter and select the appropriate channel (alpha is elected by default). That's all it takes to achieve this effect.