Hi Zolee,
I haven't seen any official confirmation from Larian concerning a Dragon Commander pre-order option on Steam, though judging from Original Sin's Kickstarter page, it'll be on Steam the day of release:
"Digital copies [of Dragon Commander and Original Sin] will have to be downloaded via your preferred digital retailer such as Steam or GOG.com"
So it's very likely there will be a pre-order option on Steam in the near future, one that includes the bonuses too (they usually have in the past).
And if you're feeling a little generous, I'd recommend just throwing down $65 in support of Original Sin on Kickstarter; you get a copy of Dragon Commander and Original Sin on release for donating.
