[Pursuivant]

You can easily scale the threat level for a given monster by adjusting levels of ST/HP, DX/Basic Speed, DR, and offensive powers such as innate Attacks.

Use DF monsters as a starting point, then "nerf" them as necessary to fit the power level of your campaign. Call them "dwarf" or "very young" versions of the monster if you need to.

Alternately, change the circumstances of the encounter so that they favor the PCs. Certain DF monsters become far less scary if you can use ranged attacks, if you can attack from above, or if characters have time to intelligently plan against them.

Change their role. Instead of using DF monsters as "routine" encounters, use them as "bosses" or "sub-bosses".

Alternately, change the way in which certain DF monsters are used. They might become much less scary opponents if you must sneak past them or negotiate with them rather than kill them.