End of the story:
After fiddling with the permissions of the integration account, DCOM, service activation, etc. without any luck, I finally simply disabled ICE validation in the continuous integration build, while still keeping it in the local build.
To disable ICE validation you can set SuppressValidation to true in the .wixproj file:
<PropertyGroup>
<SuppressValidation>true</SuppressValidation>
</PropertyGroup>
Or pass the -sval command line option to light.exe.