I've never heard of a VTB being done with a CPI adjustment, typically it's just a straight mortgage, either interest only or amortizing. Rates are whatever can be negotiated. Which is why I think a CPI adjusted mortgage could work. You'll likely have to educate your buyer on the possibility, and the advantages to them. (lower headline interest rate, and the CPI increase to the principal amount would be tax deductible interest)
You might also be able to find someone who would take a first mortgage at 1% plus a CPI adjustment every year.
For other alternatives, there are also land leases. Similar to Greg's MHPs, you just own the land and lease it to someone who owns a building on it. These are popular in England, and are very often set up so that the rental (typically for 100 years or more) rate goes up with their equivalent of the CPI. They also have funds that invest in these, which may be open to a foreign investor, I'm not sure. You'd then have currency risk, but you could always hedge that out if you preferred.
Regards,
Michael