Oil/Fat substitutes in bread
Well, it sounds like the answer should just be to soften your margarine first.  Either your margarine is ice cold or your machine doesn't need very long if you're ending up with little studded bits of margarine in your crust - that's very unusual.

Can you add oil? Sure.  Try adding some olive oil instead or just vegetable shortening .  There's a little water in margarine and butter, its an emulsion - about 16% of it - so if you're going to add pure fat then technically you'd need to add about 1 tsp of water as well.  Will 1 tsp of water matter overall? Probably not...but its there.

(Overall that recipes looks a bit low on water to me also - I'm not sure how that would effect the margarine mixing though.)