I applied for my wife recently. She is in Pakistan. I am in UK and I filled online form VAF4A. When you register at the website and start an application, there are two options: Apply for myself and apply for someone else. You should select apply for someone else and fill out the VAF4A form online. You will also need to download and manually fill VAF4A Appendix 2. There are some other appendices so I don't know if they are valid in your case. I don't think you need your wife's signature if you select 'Apply for someone else' option, she will need to provide bio metrics, which you can schedule once you have filled online form and made a payment.
Once you have submitted your application and paid for visa and health surcharge, you can print the online form in pdf and email it to your wife, you will also need to email her the payment confirmation and appointment confirmation emails if they are emailed to you and not to her. She can take them with her at her bio metrics appointment.
You will need to send your docs to sheffield:
UK Visas and Immigration International
Po Box 5852
SHEFFIELD
S11 0FX
The list of the documents are explained in the following post, please note this procedure is for applications from Pakistan but it should provide you a general idea, if your wife is not in Pakistan.
http://www.immigrationboards.com/immigr ... 93554.html
Please note this is for someone applying their first entry clearance spouse visa and they are not in UK.
I'll be travelling so I won't be able to reply anytime soon.
Good luck!!