Not sure about BS/rgn. But there is a really decent indeapth BS/INV build on the US forums.
spines/invul. most definetly!
They rock the hardest n kick loads upon loads of [censored].
Havent really tried all the others but hey, i have spines.
Ar'cane lvl 32 union scrapper
hmm sorry bout that. Replied to the wrong post! lol.
Evrybody just ignore what lil old idiot me wrote above...
Sorry.
Look up EvilGeko's BS/Regen guide on the US forums. 
Broadsword / Regen is a great combo.
I've got a 27 BS/Regen scrapper and I'm doing fine.
The endurance cost of your primary is almost balanced by Quick Recovery. Stamina appears to be more of a luxury than an essential when you have regen as your secondary.
I know it's cliche but there isn't really a 'right' way to build a BS/Regen scrapper.
EvilGeko's guide for BS/Regen can be found here
It should help you to build a scrapper to fit your taste.
or, for the I6 version of that...
http://boards.cityofheroes.com/showf...Number=3929981
But seriously, BS/regen is an uber combination. Broadsword does enough damage out of the box that you can get your regen slotted up well comparitively early. Although there are a couple of minor issues I disagree with Gecko's guide about (it is well worth slotting IH with an extra 3 heals, the extra can often tip the balance, and I like to use a little more accuracy in attacks than he does (with those slower, heavier attacks, you definitely want them to hit)) it's fairly good as far as the broadsword utility powers go.
MoG still sucks.
Do not go gentle into that good night.
Rage, rage against the dying of the light.
whats a good build for a regen broad swrod scrapper