these parts and the programming are available as a retrofit option - but it won't be cheap
It might be best to get the hardware (ebay) and fit to the bike, then seek to get the programming done. But don't think its dirt cheap, BMW charge for legitimacy of any optional extra.
Effectively you are buying
1) the software license
2) the right for it to be covered with diagnostic support it might need at a later date
3) the right for any future programming improvement that may become available during an i-level update of the bike.
It was less than I expected. ASR option is about $500, I fitted the new left switch gear and indeed can programme the DME, Cluster and ZFE as required, but without the VO (vehicle order - the list of toys BMW built the bike with) the modules fail to communicate with each other and it doesn't work. Having quoteed almost nothing, they then needed me to buy the licensing (I knew I'd need but the dealer didn't !!!) which ended up at £140, but then they took 4 hours to do the paperwork so all BMW systems now know its a legit feature of my bike.