Okay I see how to do it now:
[myclassdef propertyDefinitionWithName:@"firstName"].attributes =
[SCTextFieldAttributes attributesWithPlaceholder:@"enter your first name"];
If that wasn't possible I was hoping for something like this:
SCClassDefinition *myclassdef =
[[SCClassDefinition alloc] initWithClass:[myclass class]
withPropertyNames:[NSArray arrayWithObjects:@"firstName", /*etc.,*/ nil]
withPropertyTitles:[NSArray arrayWithObjects:@"enter your first name", /*...,*/ nil]
usePropertyTitleForPlaceholderTextInsteadOfLabel:YES];
Thanks!!