Suggestion: Chain keywords to emotes

[Kirika-]

If you mean you want a certain set of keywords to automatically trigger a emote action at anytime when typed in chat, that would be problematic at best.
Without timing to allow for the different animation duration of emote actions to take place and complete, for example a "Hi, great to see you again" would either get stuck playing the /wave or /lookout emotes, ignoring the other.
A macro is the best solution.

Using a macro for your first example:
/s Hi,
/wave motion
/s how are you?

The "motion" variable added after the emote action name allows execution of the emote without it's action/flavor text appear in the chat window. You would be observed is "Hi," "how are you?" with your character waving as you speak.

For the second example:
/s I don't see
/lookout motion <wait.1>
/s anything

The <wait.1> variable adds a 1 second pause before executing the next line in the macro, so in this case the result is the character saying "I don't see", looking around for a second, and then lastly saying "anything".

Using the <wait.#> variable, you can also string together emotes actions to create some cool effects.
Just observe the duration in seconds each emote action has and then figure up a delay to allow that emote to "play" before going to the next line in the macro.
I have a couple I use occasionally:

This one gives the appearances of encountering a confusing situation, then coming up with the solution.
/huh motion <wait.2>
/think motion <wait.6>
/eureka motion <wait.3>

This one I'll sometimes use while waiting for the dungeon/raid/trial to begin while inside the starting ring... My getting ready for battle emote macro:
/estretch motion <wait.8>
/bflip motion <wait.2>
/powerup motion <wait.4>
/megaflare motion