Webutil does work with Forms11gR2 64-bit.
We've just used it very recently for this platform.
You need to make sure you have the correct version of the jacob libraries.
Forms 9.0.4 and older with WebUtil 1.0.5 (beta) and older - Jacob 1.0.7
Forms 9.0.4 and older with WebUtil 1.0.6 (beta) and older - Jacob 1.0.8
Forms 10.1.2.0.2 - 10.1.2.3.0 with WebUtil 10.1.2.0 - 10.1.2.3 - Jacob 1.0.8
Forms 10.1.2.3+ (Forms Bundle patch) - 11.1.1.x with WebUtil 10.1.2.3 - 11.1.1.x - Jacob 1.10.1
Forms 11.1.2 with WebUtil 11.1.2 - Jacob 1.14.3
(Taken from Michael's post Jan.2012)