Choose Show Other Scripts from SpamSieve’s SpamSieve menu. Copy the files from the For Emailer Users folder into Emailer’s AppleScripts folder:

You may need to quit and re-launch Emailer in order for it to notice that you have installed the SpamSieve AppleScripts.
If you want SpamSieve to color messages that it thinks are spam, set up a mail action in Emailer that looks like this (using the Define Actions… button to set the “Run the AppleScript” action):

If, instead, you want SpamSieve to move suspected spam messages to a Spam folder (that it creates automatically), set up a mail action in Emailer that looks like this:

Now proceed to the Do an Initial Training section. To train SpamSieve with spam messages, select one or more of them and then choose SpamSieve - Train Spam from Emailer’s Scripts menu. To train SpamSieve with good messages, select one or more of them and then choose SpamSieve - Train Good from Emailer’s Scripts menu.
SpamSieve will process new mail automatically. If you ever need to manually ask it to sift through a mix of spam and good messages, select the messages and choose SpamSieve - Color If Spam or SpamSieve - Move If Spam from Emailer’s Scripts menu.