Just in case you didn't find it, noting your quote, you can use the -m switch to create a millisecond timer.
/timer -m 0 1 <command>
I wouldn't recommend anything too extensive for the <command> section, as it will be called eveery millisecond (1000 times per second).
Please note that while this is as accurate as you can get, there is a chance that it won't execute exactly on the millisecond, so that you might get (for example) 950 calls per second versus 1000.
If it's important that you get the correct timing, add the -c switch,
As you noted, /help /timer has all this (and more) information.
