Not really that much. The main difficulty is actually determining the annual rate of inflation, putting together an adequate basket and keeping it up to date every year.
Then all public affairs (minimum wage, tax brackets, pensions, wages of public servants) could be automatically tied to the RoI, still allowing for legislatory interventions in cases of mismatches, grave economic crisis, etc. With wages in the private sector it's naturally more difficult, though easily manageable with strong trade unions and collective bargaining. The only problem is that most of the western countries did a pretty good job at destroying these over the past few decades.