Makoto Hatanaka

I've done similar thing before. At that time I used for loop in for loop in for loop … … to go through all patterns and naming layers uniquely like layer_111 layer_112 layer_121 … …
So you'll need to either make those layer files outside of Houdini or by using default layer, pick individual pattern by using for-each loops and export layer files by agent definition cache node.
I can prepare a sample if you like.

As far as I know, the fbx file you're loading should have multiple takes if you go with fbx way.
So you'll need to combine all your animation files into one some how.

Otherwise as you probably know already, use agent clip sop to add exported .bclip to stream.
I actually prefer importing fbx once and use agentROP to export each components for custom primitive attributes and edited transforms by CHOP for __locomotion__. hip file gets huge very quickly if you keep them in one file though