Well, you can do it in two ways, and in both the cases your keyboard must have an in-built sampler.
One simple way is to load Indian instrument patches on your sampler keyboard. If you have a keyboard that can read AKAI patches, for example YAMAHA MOTIF, KORG TRITON, then you can simply load Indian instruments Akai patches from a special 'Akai - formatted CD' which comes as a part of 2 CD package of SwarTrax. Once you have loaded the patch, you can easily play Indian instruments on your keyboard. Also, you can simply play a MIDI file ( SwarTrax contains over 1000 rhythmic and melodic loops) using the loaded patches. Thus you can actually play Tabla, Pakhawaj, Sitar Sarod from your keyboard.
But if your keyboard cannot read Akai patches but can import individual .wav files, then you can load individual .wav files on your keyboard and then map to specific keys. This way you can manually build the patch and then play through your MIDI keyboard or other MIDI devices connected to your computer..
Another option is to load Akai samples on a hardware sampler and then route your sequencer/keyboard through the sampler for playing Indian instruments