Help with Eudora Script

I want to send an email from an AppleScript using Eudora, but cannot figure out the syntax for setting the personality - the From: line. I’ve got this much:

tell application "Eudora"
	activate
	set x to make message at (end of mailbox "Out" of mail folder "")
	set field "To" of x to "ToWhom"
	set field "Subject" of x to "SubjectLine"
	set field "" of x to "MessageText"
	-- I want to choose one of three personalities in this line. 
	queue x
end tell

I’ve tried a bunch of options and every one has errored.

Thank you, Jaques;

Among the many variations I tried, I did not think of that one.

Adam