You can't add discrete commands to R50 remote. But if you were to get cheap UEI made remote like Onn 6 universal remote from walmart:

[Link: walmart.com]

Using Samsung tv code 2051, the advanced code (efc) for hdmi 2 is 00030. To map it to key on Onn 6 remote:

1. tv
2. press and hold SETUP for two blinks, release
3. enter 9 9 4
4. tap SETUP for one blink
5. enter 0 0 0 3 0
6. pick a key

Now use the Onn 6 remote to teach your R50 the hdmi2 command.

Other codes can be found here:

[Link: avsforum.com]