Hello and thank you for your question.
I'd like to start by trying to put your question into perspective. For a simple case, it might take an hour or two of my time to prepare the Form 3115. More complex cases can take much longer. Generally, it takes less time to simply prepare the form then to teach someone else to prepare the form...
That said, I can provide you with my information via what JustAnswers calls an "additional services offer." We can talk on the phone and e-mail any necessary documents and information. I would suggest you send an e-mail containing the questions and a copy of what you have done so far on Form 3115 to get started, then arrange a time to talk.
A change from the cash to the accrual method will require that you have two properly prepared beginning balance sheets for the change year: one on a cash basis and the other on an accrual basis. From this, you can generally calculate the required adjustment under IRC 481. I'd strongly advise you send those too if you want to do an additional services offer.
I'm a little concerned that you might be an owner of this business, in which case your S-corp isn't a S-corp. It's a C-corp because non-resident aliens cannot be S-corp shareholders (IRC 1361(b)(1)(C))...
That said, most CPA's won't prepare a Form 3115 for less than $500... I understand that's probably well beyond what you're looking to pay, but keep that in mind when you get my offer which will still be for substancially less.
Thank you again for your question.