Any procedure to summon cthulhu is made up, so make one up. Or if it makes you feel better I'll make one up:

Cook long pasta to aldente, then spread it all over the floor, then roll around it in while praising the noodly limbs of cthon, and asking the eldritch god to wrap you up and take you to the realm between dimensions. And I dunno, pat your head and rub your tummy at the same time to confuse yourself. Confusion and the unknown are the key when it comes to eldritch beings. Add spooky LED lights that shift from green to purple.