You can try to find a remote your OSSC responds to with its green LED blinking. If you don’t have any working remote yourself, you may want to ask friends, family members or neighbors, if you may be able to test their remotes. After finding a suitable remote you can use it to program your L336… and after that: programming your OSSC to accept those new codes (as in the description linked by ‘SavagePencil’).
If you want the original IR codes and you don’t have any working L336 at hand to copy the codes and mappings from, you can use an USB IR transmitter like this:
… or similar in conjunction with (Win)LIRC and this script:
… to let the transmitter send the original IR codes to program your L336 with them.