Learn English – Formal way to say “Somehow”

According to Randolph Quirk et al.'s book on English grammar, structures like X is Y, where X is a noun describing the noun X are in "a copular relation". Y here is called a complement.

We put an indefinite article before complements in such structures if Y is not unique: "Mark is a programmer". However, if the complement names a unique role or task, we may use either a definite or a zero article: "The user is (the) administrator" (that would imply that there's only one administrator position); "John is (the) captain of the team."

P.S. Y may be a complement or an appositive noun phrase ("John, (the) captain of the team.").

We have two issues here.

1. Grammar structure.

   If you look at the original sentence you will notice that the subject is the user and the first part describes by what means the user does something:

   Using a sample page of a website and having access to the properties of each element, [the user] [can] [generate a wrapper for similar pages.]

   The same is true for is able:

   Using a sample page of a website and having access to the properties of each element, [the user] [is able to] [generate a wrapper for similar pages.]

   Once you change to enable, the whole first part becomes the subject, the comma is lost and the user is the object of the sentence (hint: the structure is always subject-verb-object, SVO)

   [Using a sample page of a website and having access to the properties of each element] [enables] [the user] [to generate a wrapper for similar pages.]
   
   

2. Style.

   Whether can or is able is the better choice is
   a) a question of personal style and
   b) context.

   In my experience the "more complicated" or "formal" word can be better, but is not always neccesarily so. In this case, my gut feeling (I'm neither a linguist nor a native speaker) would be that can focuses on the fact of what the user does, enable points out the possibility to do something he previously couldn't. English is a language that (compared to other languages I know) gives less precedence¹ to "specialized" words than others, so frankly, if can fits, I'd use it. Overuse of "formal words" can appear forced and even unnatural, but that is probably something for another SE site.

¹ See? I'm falling into the "big words trap" myself..