XCart integration into Typo3

We need to develop an interface or extension that integrates XCart 4.0.18 into Typo3 utilizing already existing user groups and user data without doubling user data, allowing for all the comfortability that xcart offers? How would you plan the integration? What are the challenges you anticipate? What ideas can you come up with. Assessment of your bids will be based on: 1. Your ability to understand our needs and the technical challenges 2. How you plan to add value and the implementation idea you propose 3. Competitiveness of your bid in terms of pricing and timeframe 4. Examples you provide using Typo3 and X-Cart - I don't want to see anything else please! Please only bid on this assignment if you have thorough knowledge of Typo3 and XCart!