Direct traffic to pool member according to client connection by bytes

This is a strange requirement, but here goes:

I suspect you may have to do your own accounting.

For each connection, you can initiate

TCP::collect

With no argument specified, the event

CLIENT_DATA

Otherwise, you can specify bytes, and the event will fire after the set number of bytes (at least) is received.

Once you've reached the counts you want then you can call

pool

On the small chance that you're at a service provider trying to do traffic accounting, I am almost certain there are more efficient ways of doing something like this at scale, and you should probably engage with a consultant or architect to evaluate.