Thanks guys for your answers ...
@James: I'm extending the MovieClip class and then creating objects from inside the cllass (including the textfield) in code, which complicates things a bit (if only in my fragile brain). The weird thing is that I've set buttonMode = true on the MC, and it applies to everything except the TextField, when it reverts to the caret (or just the pointer if I set Selectable = false on the TextField).
@ForYourOwnGood: Point taken about usability, but I want the textfield to be a seamless part of a bigger object, and it just doesn't feel right without the hand cursor. What you supplied sounds like just what I need, but it looks like it's Flex specific? I can't find the equivalent in Flash (specifically CS4), despite trawling through LiveDocs. Am I being dim? :S
Thanks again for your help, both of you :)