I' pull the sample up through the dipstick tube, but I have a pump which will do this.
You can clean the tranny pan drain plug, then pull the plug and let the fluid start draining (into a nice clean pan). Let it drain a bit, then put your clean sample bottle in the stream and catch a couple ounces.

If you can find an active AMSOIL dealer locally, he/she should have some sample bottles (and maybe a suction pump, too). Otherwise, check with your local truck dealers--many of them have sample bottles and can help you.