Hi Santiago,
One way to achieve this can be manually constructing a continuous time series by aggregating data from individual expired futures contracts. Use reqContractDetails() with a defined Contract object (including includeExpired=True) to obtain all related futures contracts. For each contract, create a new Contract object, set includeExpired=True, and use reqHistoricalData() to fetch 15-minute interval data. Finally, aggregate the data chronologically, handling rollovers.
However, there might be other approaches to do the same for which I would suggest you to reach out to the IBKR support team here and they might be able to help you with the same.