A pancake compressor is ideal, but if you don't have the money or space for it, then I would suggest getting a trigger activated CO2 inflator like this one that can dump out all the compressed air at once when the trigger is pulled:



So far I have 100% success rate with it, seating 12 road tubeless ready tires without using soapy water, even tires that have been removed from the rim before. I used 20g cartridges, and each cartridge left 120 psi in each 700x23c tire after the beads popped loudly into place.