Mix the lot up. Quantities should be treated as highly variable - adjust according to taste, and add water as needed to get it to a spreadable sort of consistency.
Using warm water would help dissolve the miso (I suppose you could dissolve it ahead of time, on its own, which might help).
I was making myself "cheese" toasties at the weekend, and came up with this - it's an adaption of a couple of other similar recipes I've seen. Worked very
well, I thought - had a nice "bite" to it (I always liked *strong*-flavoured cheeses).
No idea whether it keeps in the fridge - I ate all of mine during the course of the afternoon :-) But I suspect that it might not keep too well - it was going a bit
hard around the edges of the bowl after a couple of hours. It might be OK covered, though.