No.

la_data_oenb

is somewhat misleading. It is meant to be used to indicate that a signal will be driven from the logic analyzer instead of something else, and drive the select pin on a mux somewhere in the user design. In reality, it's just another set of inputs like

la_data_in

and can be used as such, making a total of 256 inputs.

like this yes?

That's the general ideal, although I don't recall the signals ever being so friendly and polite.