Here is the user guide tells you how to update your R4i sdhc to support DSi V1.4.2 system.
First, you need to buy R4i sdhc, and the R4i sdhc you have is like this
1. First, format your SD card, and download the latest kernel 1.37b here
2.Extract the file and copy the files (R4iMenu,moonshl2 ,moonmemo, r4.DAT) to the root of your MicroSD card.
3. Download the update file package here
Extract and copy the files(fwup142.nds ) to the root of MicroSD card.
4. Insert MicroSD card into your r4i-sdhc card, insert r4i-sdhc card into your nds\dsl\dsi\dsill\dsixl
5.Power on your console and press button "A" to run the upgrade file fwup142.nds.
6. Finish the update and enjoy your game on V1.4.2
Notice: Don't power off the DS console, do not unplug the flashcard or SD card during the update procedure