If your OSSC responds to your Toshiba CT-877 remote control (= the green LED flashes), you just need to set up your OSSC to work with the CT-877… like described here:
To configure OSSC for a new infrared RC, find a suitable manufacturer code (e.g. from Toshiba, NEC etc.) so that OSSC green LED blinks when remote buttons are pressed. Then cycle OSSC power on while holding PCB BTN1. A target function name (e.g. “MENU”) is displayed of the character LCD. Press the corresponding key on the remote control, after which you’re prompted to confirm the new code if signal was detected correctly. Press the same key again to confirm, or PCB BTN0 to go to previous key (loads default keymap if pressed during configuration of first key). Continue programming rest of the functions, after which new keymap is saved and OSSC returns to normal operation.