Hi,
In theory, it should be possible, UcheckCMD Portable not being tied to any Windows account.
However, I strongly advise you to test it before (on a VM, for exemple), because a lot of software write files in the %APPDATA% directory of the user account logged in at the moment of the installation.
Since it's not really an account like the others, SYSTEM has not such a directory so there is no way to tell how the installers will behave.
Regards.