The easy way to strafe is to translate the player depending on whether left/right is pressed (see TranslateEntity); the more complex way is to use vector math for x and z velocity (bit early for that, I think)
Actually, from his initial post it sounds like he is already doing things the easy way and doesn't like it. You'll need to use some vector math for what you want (or rather, use the TForm commands to do some vector math for you.)