This quotation is commonly misattributed to the monster in Mary Shelley's novel, but it is actually stated by this same character in director Kenneth Branagh's movie adaptation of the book. The creature asks his creator, as he does in the novel, for a companion, a female who would be created like him and, most importantly, look like him. He says that he is miserable because he is alone, and a companion could not only keep him company but also provide him with the compassion that he lacks. Humanity, including his own creator, has treated him horribly. He does, truly, long to love and be loved, and to have the kind of relationships that he has witnessed among the members of the DeLacey family. However, he promises—in different words, but in both texts (the movie and the book)—that if Victor does not give him the chance to realize a loving relationship, he will cause misery and pain to Victor and his loved ones.

The quote, "I have love in me the likes of which you can scarcely imagine and rage the likes of which you would not believe," is not found in Mary Shelley's novel Frankenstein. It actually comes from Kenneth Branagh's 1994 adaptation of Shelley's novel.

While the quote is not found in the novel itself, there is one quote which is close to Branagh's adaption. This quote is found in chapter seventeen of Shelley's novel: "If I cannot inspire love, I will cause fear; and chiefly towards you my arch-enemy, because my creator, do I swear inextinguishable hatred."

While the quote from the novel does not directly speak to the love the Creature possesses, as does the Branagh quote, it does speak to the rage the Creature possesses. Given the fact that the Creature is asking Victor to make him a mate, the Creature is trying to impress upon Victor the two choices he (the Creature) has in life: inspire love or inspire fear.

In Mary Shelley's Frankenstein, on what page does the creature say, "I have love in me..."?

This quotation is actually not from Mary Shelley's novel, but, rather, it comes from Kenneth Branagh's film adaptation of the book starring himself as Victor Frankenstein and Robert De Niro as the monster.  The movie was released in 1994, and to be frank, it is not a very good adaptation of the novel; it seems, to me, to be intended as a horror film rather than a movie adaptation of an existing work.  There are several scenes of gratuitous horror designed only to be revolting -- most especially including the "mate" Victor fashions for his creature (there is a twist here that I am loathe to reveal) and her response to realizing what she is.  

At any rate, this particular line does seem to encapsulate many of the ideas that the creature expresses to Victor during his request for a mate.  He says, in part, in Volume II, Chapter IX, 

I will revenge my injuries: if I cannot inspire love, I will cause fear; and chiefly towards you my arch-enemy, because my creator, do I swear inextinguishable hatred.

The creature has tried to be loving: to the De Laceys, to the drowning girl in the forest, and it has only ever blown up in his face.  He is met with hatred everywhere he turns.  He claims that he began life with "benevolence and generosity" (Vol. II, Ch. VII).  But now, however, having been neglected and abused and insulted in every possible way, if his creator will not give him this one chance at a loving relationship, then he will work toward Victor's destruction.  

Just as the creature identified humankind as a species that was capable of great good and great evil, we now see this dichotomy reflected in him.  This is probably the best proof we have that he is, indeed, a human being, however frightening and ugly.