Re:Studio Instruments - Drum Kit - Latin Drums???
I am 90% sure the Studio Instruments drum kit cannot load samples or other sets. You are stuck with what they give you.
What version of Sonar are you using 8.5 PE has session drummer 3 which can load other kits and samples, I am not sure what there is in the way of latin samples. I have not seen this personally yet but it looks like its based on a conventional kit so loading latin samples may not be that intuitive. Earlier PE versions had Session Drummer 2, I think it was possible to change sounds here too.
You already will have TTS, this has Latin percussion as part of its GM drum kits.
If the TTS percussion does not cut it a cheap option get a latin instruments soundfont and use it in SFZ. Google for soundfonts and you will probably find some free ones of varing quality.
A good $99 option is Kitcore, the Delux version has several Luis Conte latin kits giving a wide variety of latin sounds and a whole lot of MIDI grooves played by him.
If you can afford a bit more there is EZDrummer + the latin percussion EZX. I dont have thes EZX but the toontrack stuff is excellent. You will also get a pile of latin MIDI grooves to use with it. You probably get fewer kits with EZDrummer than Kitcore, but you have more control over the sound.
Also with both Kitcore and EZDrummer you will be getting regular drumkits that are a lot better than the one in Studio Instruments, and a lot of Midi grooves.