Using userid if condition.. help

[kyokushin4life]

Hi there i'm trying to use an if condition statement for multiple users.

eg)

<if condition="$post['userid'] == 602">something happens</if>

I would like this statement to be used for multiple users, for example userid 602, 345, 123 etc..

How do I do this in a statement ratehr than using duplicates? thank you.