Hamelman's "Workday" bread stiff culture

Yes you can. In the section of the book where he explains starters, Jeffrey himself says that it doesn't matter whether you use stiff, or liquid, or in between starter.

He says, in one of his letters published online,

While it's good (and important in my opinion) for today's ever more skilled bakers to know how to convert a liquid starter to stiff and vice versa, there's no reason to necessarily do that, because the amount of mother culture going into the builds is very small. Small adjustments in flour or water will compensate at the time of the build so that levain consistency is correct. 

You can read more of what Jeffrey says here

The only thing that matters is the number of grams of flour in your starter. In his recipe, (I linked it from Googlebooks), Hamelman asks for half Tbsp of stiff starter which weighs 5g. You can assume that it means 3g of flour in his starter (and 2g of water). So you use 6g of your starter instead.