Jaksta Recorder for Slingbox may operate your remote control just fine with the default settings. However, some devices may map differently.
If Jaksta is not changing channels as expected, try configuring the key maps for your device.
The easiest way to find key maps for your remote and box is actually to google "slingbox key maps <your remotes name>" or something similar. The slingbox.com support forums also have a lot of them. Again google will help you find them for your particular setup.
Once your have them your can change them for your device in Jaksta Recorder for Slingbox.
Select your device and then Configure Selected and then the Key Map tab.
Ensure you use the correct formatting. Ie write 9 as 009, 20 as 020 etc.