Answer: First: my fellow Americans, remember that the term "crotchet" is what the British insist on using when referring to a quarter note. If you look at the below image you'll see that a crotchet triplet can be understood as two quaver (eighth notes!) triplets with ties. It's a catchy sort of syncopation. If you sing the quaver triplets first without ties and then start adding the ties, you'll get the feeling of the crotchet triplet. Each quaver triplet of course is taking the time of one normal crotchet.

You could also set a metronome going at the quaver speed, thinking of them in groups of threes. Then sing a note for every two ticks. This might seem tricky at first but once it's in your head it's hard to forget.