Good News, I found the source code. It's on an old floppy
Bad news: My present workstation does not have a floppy drive.

But I remember how to do it.

Embed the following in the character stream. First the escape code then the characters.
Underline is CHR(027)+"&d3D"
Italic is CHR(027)+"(s1S"

I can't fing the bold code, but if you google it, something may pop up.

Of course this was in the days of @say and stuff like that.