tDCS is a steady state current flow and so does not have a frequency.
tACS is the electrical stimulation that has a frequency setting. Some tACS studies here.
So if you want to induce your brain to work at a specific frequency you should try tACS. tACS is availble on the foc.us v3
It is possible to use EEG and tES at the same time if they are from separate devices.