The manufacturer used by lotus is no longer in existence
However we had been dealing directly with them for years..
The products used to colour wheels are made by a company call Freilacke
I have one product code for silver that was used on lotus wheels (could poss be more)
The code i have is
Sport silver is WO1838MOE20A
Our local wheel refurb company uses Freilacke to when we need help, thats who we go to
Any wheel refurb company that uses the product may be able to help, however some of the colours used are a powder, so you may find it difficult to find a 'wet' solution (I think the silvers where a painted top coat, hence silver over black etc etc)
When in business the wheel manufacturer where always very helps with info, sadly all that knowledge is now gone forever