I have seen a number of posts here about removing the crankshaft bolt on Civics. Most have recommended the special 2-part Honda tool - which is expensive. I saw a YouTube of a guy doing it with a chain and allen wrench and it works like a charm! You wrap the chain around the motor mount directly above the crank several times to secure it. Then loop the chain around the pulley (direction depends on whether you are loosening or tightening) and insert an allen wrench through a chain link and into one of the holes in the pulley. Now with a 17mm socket (or my 98 Civic) I can unscrew the bolt (with a big breaker bar!) and the chain/allen holds the pulley in place. Sweet!

 

I had to heat mine up with map gas for over a minute and hit it with a 600ft/lb impact hammer. Not fun.

 

Don't bother with holding the crank pulley tool, good 1/2" impact and air compressor. Work smarter not harder.

 

jam a screw driver in the flywheel through the inspection hole, and loosen.

 

If it's a '98 civic there are no holes in the crank pulley. Some of the '92 - '95s do.

 

like posted above lock the flywheel and use a power bar or use a good strong air gun with a big compressor.
if it doesnt go with either try heat it.
i had a mates car before and was fitting a n1 pulley. tried all options to open it and it wouldnt give at all.
got him to head into my work where we have a huge impact gun for taking off truck wheels and that worked a treat.
so if these options fail for you try a local tire place