[R] test for difference between non-independent correlations

[Avril Coghlan]

Hello,

  I am wondering whether there is a way to
test whether two non-independent correlation
coefficients are significantly different, in R?

I have an experimentally measure variable Y,
and two different variables X1, and X2, which
are predictions of Y that were predicted using
two different computational models.

I would like to see whether the correlation
of Y and X1, and Y and X2 is significantly different.
Since Y appears in both correlations
the correlation coefficients will be non-independent.
(so you cannot use a Z test like you would for
comparing independent correlation coefficients, I think).

I have read that there is a test for comparing
non-independent correlation coefficients, by
EJ Williams (1959) and Steiger.
There is also a test called Hotelling's t test.
I'm wondering does anyone know whether I can
somehow carry out any of these using an R package, or compare
non-independent correlations using R by some
other method?

I will greatly appreciate any help,
thankyou,
Avril Coghlan
(University College Dublin, Ireland)