Typically this is used in two ways: 1) To express great emphasis. ("A hell of a [subject].") 2) To express a large quantity. ("A hell of a lot of [items].") So you could use it as: "A hell of a time." - Indicating that the time or event was either really good, or really bad. Context determines the meaning. "A hell of a man." - Indicating that the man was exceptional and to be admired. "A hell of a lot of work." - Indicating that it's much more than just "a lot" of work. Typically when this is used to describe a subject it will be in a positive context. Using it to describe a certain time period is the only instance I can think of where it is possible to have a negative meaning. Be careful where you use this phrase, however, as some people will find it offensive.

Just to add to what the others have said, looking at the grammar of the phrase... The expression is always '..... a hell of A...' . Note the word 'a' at the end. The expression has to end with an indefinite article, followed by a singular countable noun. That is why your suggested expression 'a hell of trouble' was wrong. 'Trouble' is an uncountable noun, used without an article, so it can't follow directly after 'a hell of'. Paul solved your problem by changing it to 'a hell of A LOT of trouble.' If you look at all the examples which Paul and Jonathan have suggested, they are all with singular countable nouns ( .. a long way ... risky decision.. a time .. a man). Finally, if you think that 'hell' might upset someone, you can always tone it down and use the less offensive 'heck' instead. "It was a heck of lot of trouble" is less likely to offend people's sensibilities.

There are two different expressions here, don't confuse them. You need to say: It's a hell of a lot of trouble to implement it. This means 'it is a lot of trouble to implement it.' In the same way 'it cost us a hell of a lot of money' means 'it cost us a lot of money.' The usage of 'a hell of a...' is different. It is used to mean 'really' or 'very.' It is a hell of a risky decision = It is a very risky decision. It's a hell of a long way = It is a very long way. I hope you see the distinction.