Lip-synch or eyes blinking via texture swapping is usually done with some code, so the code can trigger the swap according to specific events. Blinking could be something like "randomly swap to the shut eye bitmap then immediately back to the open eye bitmap, but never allow the frequency to be faster than 3 seconds."…
a useful alternative is combining sprites/sequences to a single texture and then animating texcoords, however then you loose tiling ability (unless more costly pixelshaders are used). emulating the "coded" effects as Eric pointed out, would be best done via maxscript, else you would need to set too many keys manually.