Now to start with the documents required:
1) RC Book
2) Driving License
3) Active vehicle insurance
4) Original invoice...this is used to compute the Road tax amount
5) PUC slip
6) 1 plain paper
7) Local proof...not compulsory
In case of "change of registration" u need to have NOC of vehicle previous registration. It takes some days before u r handed over the new number.
Get the xerox copy of all the above mentioned documents (if u haven't, there's a xerox shop in the RTO compound) and collect a FT document from a store(its free of cost) just outside the main RTO building. There will dozens of agents asking u to fill the form on ur behalf...just ignore them..the form is very simple to fill...just copy the details from ur RC book.(The form is in English).
After u have copied the details on the FT form from ur RC book, just write an application on the plain paper to the Regional officer RTO (Mr. Nikam) asking him to approve ur case to file road tax. Take the completed FT form and application to Mr. Nikam's office (enter RTO main building and take the 1st right...u'll see his office and name). He will sign on the form saying "Accept Tax". After this is done rush to the lady at the extreme corner on left..this lady will look at the invoice and compute the road tax amount on the FT form. Next, rush to another lady, Mrs Korse, this lady will have a short look at the form and just sign it and will ask u to join the queue to pay the road tax (The amount will be the one computed by the lady earlier). This is the place I got messed up big time...got in the wrong queue...the one mentioned by the Mrs Korse was wrong...I wasted around 2 hrs in the wrong line.Lines are not that big but you have agents in the line with 1o cases at a time...and some back door entries...but can't help but wait :(
Get into the line for window 23...this is the one accepting road tax for outside vehicles. After some wait and patience u'll finally get ur receipt indicating that ur vehicle has paid the Maharashtra road tax :)
The help window won't be of much help so please don't waste much time there. If you face any troublesome issue at the Office ...Mr. Nikam is the best person to contact..he sure helps :)
All the best and after this task is completed ...rip away ur bike in Pune's streets.