I use a spare rim & tire with innertube inflated to about 80psi (or maximum stated on the side of the tire). Transfer hose made from a floor pump hose with a head on each end. Seat the tubeless tire on the rim & add sealant, soap it up as per instructions on the pack, hook up the transfer hose and then connect it to the previously inflated spare tire. A bit of hissing and popping and you should have a tubeless tire inflated to about 40psi. Inflate or deflate as necessary!
Have thought about a lemonade bottle with the same system, they can take up to about 100psi. A tire volume is around 4 litres so a 2 litre lemonade bottle at 100psi should be able to inflate the tire to about 30psi. That should be enough to seat the bead on the rim, then top it up with a foot pump.
This works fine with a rim strip, but if you are running ust rims, using this method it can be a bit tricky. To make it easier though, I have found that if I inflate the tire with a tube first (to seat the bead), then pop off one bead and take the tube out, proceed as before with the sealant and air transfer and it goes on a lot easier. Seems to strech the tire into shape ready for tubeless.
Hope this helps!