Ok... this took me way too long. The sql-management studio tool is just not up to simple things like this (which I've noticed before when looking for where to set the timeout on queries, and it was done in 4 different locations)
I downloaded some other sql editor package (sql maestro in my case). And behold it includes a blob editor where you can look at blobs, and load new blobs into these field.
thanks for the input!