With Channel Changer you can change the transmitting midi channel of your keyboard on the fly, simply pressing a button and a key.

Open it in your VST host application, connect the host midi input to the Channel Changer's midi input and its midi output to the midi input of a Vst instrument.

Set your midi keyboard's transmitting channel to channel 1, press and hold a button of your midi keyboard sending a CC message #105, set the desired transmitting channel pressing a key in the range C3 (channel 1) - D#4 (channel 16) then release the button: the chosen midi channel is shown in the Channel Changer's GUI.

In order to come back to midi channel 1 (reset) simply press a button of your midi keyboard sending a CC message #106.

You can change the CC messages to be used for changing midi channel and resetting to channel 1 through the relevant drop list in the Channel Changer's GUI.