Ok, I have updated the concrete mod with a bucket, and more complex crafts.
the concrete source is only obtainable in creative, if you have buckets turned on in the settings.
the crafts are:
cook compressed cobble to give a bag of portland cement
(or cook stone if moreblocks is not installed)
craft a bucket of concrete by surrounding a water bucket with bags of portland cement in the craftgrid
bake a bucket of concrete to give 9 concrete blocks (bucket is returned) if you don't want to place the liquid.
I made the abm interval configurable in settingtypes like you suggested. Default is 60, but change it so it works for you.
I don't like the idea of node timers for this because if the concrete liquid is placed, then cures, the flowing nodes may have time to flow away before they cure
also if the source is placed up in the air, the concrete may be able to endlessly propogate itself until it reaches the ground, allowing for the spawnning of infinite numbers of nodes, in ugly pillars. An abm puts an end to the flowing concrete at the end of every interval, preventing infinite node creation.
I made buckets optional look in the settingtypes (thanks for the suggestion :) )
If you decide to use sources (recommended, default) in the settings, a concrete source could still be picked up with an empty bucket.