Professor Chari and I are preparing a paper called Weyl Modules For The Twisted Loop Algebras.  A preliminary version of this paper can be found here.  This manuscript is an adaptation of the description and classification of Weyl Modules for the untwisted affine algebras given by Chari and Pressley in Weyl Modules for Classical and Quantum Affine Algebras.   These modules are also discussed by Fourier and Littelmann in Weyl Modules, Demazure Modules, KR-Modules, Crystals, Fusion Products and Limit Constructions.  

The difficulty of the extension of these results lies primarily in the twisted loop algebra corresponding to A₂.  Weyl Modules for L^σ(A₂)  is a detailed treatment of this case.  Fundamental to this paper is a straightening relation among the elements of L^σ(A₂) given by Fisher Vasta in her thesis Presentations of Z-Forms for the Universal Enveloping Algebras of Affine Lie Algebras.