Actually it can be possible to do it without or at least used as an introduction for Venom. What can be done is have a meteor/comet/happy meal/whatever crash with the symbiote in it. Brock be around thinking this could redeem his status in the Daily Bugle then WHAM!, Venom is born. You could make the black Spidey just a cameo near the end of the film as if Spidey finally got the symbiote off of Brock and is now fighting with it off of hisself. I say this cuz when have you seen a Spidey film totally accurate to the film. And making 2 films for Venom (1 to introduce the suit then the second brings Venom) is completely stupid and a waste of movie making money.