A n00b's perspective...
Just thought I'd give you guys a good laugh and throw in my 1 cent...
I am just starting ladder, coming over from SP where I played for a long time before I found Atma. So I am used to playing untwinked and not trading, so I have a different perspective on the Hammerdin.
These are my suggestions based on my limited experience. Ergo, this is how you MUST build a hammerdin!
Boost BA synergy before vigor: mainly for 5% passive to hit, because you will be meleeing well into your 40's with no AR-boosting aura. You should be walking most of the time anyway, picking fights and picking up - because you need the XP's and the items and the gold to gamble nice rare jewelry. So no zooming to the next wp.
Boost Conc aura before maxing BH: Because you will be meleeing alot, and so will your merc, both with crap weapons you found on the road. So it's something like 1 BA/1conc/1BH, repeat until you hit the transition to all hammers.
About meleeing: resist the temptation to put ANY points in zeal or a holy element. Just shop for the right weapon with +skills. I prefered zeal, for speed, you may prefer holy freeze for the slow. Of course, with Fazel I now have both.
About blocking: Since your gonna have to get close, you need to block. And since you gonna want HShield eventually anyway, go ahead and get it to slvl 5 or so as soon as possible, and maintain enough dex for max block.
Once you transition to all hammers: Make sure you have redemption, at least slvl 5 HShield, and then max BH. After that, alternate between conc and the remaining synergies.
Items: Look for resists, FCR, resists, +skills, +mana/mana per kill/+mana recovery, resists, a big belt for blue pots, FRW, FHR, resists, +light radius... Leech is only needed when you melee, and mana leech especially as you transition to all hammers. After switching to all hammers, use redemption instead of mana leech - has added bonuses of preventing resurrection and of pissing off the pasty white dudes.
Me: My scl hammerdin is just now transitioning from melee to hammers as we speak, at lvl 50. OK, I found a pretty big +zeal beatstick/some +skills and I really like to bash things. I also don't like drinking blue pots all the time. But me and Fazel are moving right along, beginning A3 NM (Maggot's Lair was a cakewalk). I haven't died yet, either, and neither has Fazzie (OK, I just got him...). Hammers near 1k, mainly for the big packs and bosses. One added benefit of the slow transition from melee is that Fazzie stays right at my lvl or 1 under.
In the end, he will end up as the same hammer spammer everyone else has, and no one will be the wiser: maxed BH/BA/Vigor/Conc, rest in HShield and one point in the utility skill redemption (maybe one in meditation, too). Just took a different road to get there, one I am kinda enjoying at the moment...
DudSpud *donning asbestos suit*