No, updates will always update to latest version: 4.2.
If you want you can install 4.1 instead. The quickest way to get 4.1 on a wii is to download IOS60 v6174 (NOT v6400, which will brick), and the system menu of the right region using NUS Downloader. Install the IOS60, then the menu. (Overwrite the menu, NEVER uninstall it!)
To make the shop work, download IOS61 and shop channel v17. Install IOS61 then shop channel.
You might be able to use waninkoko's Firmware 4.0 updater, but i'm not sure if it will install the right version of IOS60...if it doesn't you make a paperweight.
If you can, install bootmii as boot2 before trying to update it. That way, you won't brick if it fails.