'''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Overlooking the ambiguity of the question, I'll assume you want to install the MTB components on your road bike.
The cassette itself should fit with no difficulty. However, depending on its configuration, your road rear derailer may or may not work with it. If the largest cog is 30T or more, you might have to use an MTB rear derailleur.
The crank fitting is more problematic. What make and type do you have on the MTB? Many current MTBs have a 73 mm wide bottom bracket shell and use a bb to match. Road bikes universally have a 68 mm bb shell if they are English threaded.
If the MTB crank is square taper, Octalink or ISIS, you may need a different bottom bracket to match the road bike's bb shell. If the MTB crank is Hollowtech II (the spindle is built in to the drive-side crank) you are probably out of luck or will need suitable spacers. The resulting chainline will probably not be ideal either.
BTW, if your road bike is Italian threaded, the MTB crank will certainly need a different bottom bracket, assuming you can find a suitable match.