Hello Van Zyl,
If I understand your question correctly adding data to a RedisTimeSeries key from a Lua script is as simple as:
redis> EVAL "return redis.call('TS.ADD', KEYS[1], ARGV[1], ARGV[2])" 1 mykey 12345678 42
where 'mykey' is the key's name, 12345678 is the timestamp and 42 is the value.
Cheers,
Itamar