they sell conversion kits, you need VTEC conversion dowel pins, new LS headgasket (or cometic LS/VTEC headgasket), a stainless braided oil line for VTEC, a plug for the oil galley on the head, and a VTEC head (B16 or B18C)
just go on eBay and look up "LS/VTEC conversion kit" look at the companies Blackworks, BLOX, and Golden Eagle, they make good kits IMO