From TomatoCart Wiki

The osCommerce - TomatoCart Migration Tool is used to import complete store data from osCommerce to TomatoCart. The data migrated includes: Multi-languages, Categories, Products, Products Options, Administrators, Banners, Configuration Options, Currencies, Customers, Manufacturers, Newsletters, Orders, Tax Class, Tax Zones.

It is tested on osCommerce Online Merchant v2.2 RC2a. Thus we can not guarantee that this tool will work with other versions. Before installation please be sure that you have made a complete backup of your osCommerce store, so as to avoid as many problems as possible during migration. This software is provided as-is, without warranty or guarantee of any kind. Use at your own risk.

[edit] Migration prerequisites

 1. A clean setup of TomatoCart
     The migration tool is designed to import data from existing osCommerce store to a clean setup of TomatoCart store. Therefore all the data in the TomatoCart database will be removed.

2. The osCommerce and TomatoCart store must be on the same server

     The migration tool is designed to import data from existing osCommerce store to a TomatoCart store. Therefore two stores have to be installed on the same server.

3. Languages

     If you have multiple languages installed in osCommerce, please download all these language packs from http://www.tomatocart.com/translator and put them under the folder "data" before you go on with this installation. Notice that the file name must be saved as language code. Please do not include any country code. For example, American English should be saved as "en.zip", rather than "en_US.zip".

[edit] Step by step migration tutorial

How to use osCommerce-TomatoCart Migration Tool then? Take migrating osCommerce Online Merchant v2.2 RC2a default sample data as an example.

  1. Run the migration
     Copy "migrator" under TomatoCart root directory. You are directed to the Welcome page.

2.Set up the database Input database information and webserver root directory of the osCommerce Store. Leave those of TomatoCart's as it is. The migration tool will get information automatically from configuration files.