http://www.mieten24.ch/product_info.php?products_id=11
http://www.surprise-party.ch/vermietung/
http://www.erento.ch/mieten/foto_aud..._tv/fernseher/
http://www.radiobolliger.ch/service/vermietung.html
Keywords: Vermietung+Fernseher under Google.CH - hope your German is good enough to land a suitable hire ( use Google Chrome browser just in case ) and welcome to the forum and soon enough to CH.
Conference organisers might also be able to assist you:
Yes, that was my first approach. They offered me a TV for 1,350CH for 4 days hire. I suggested that was bit expensive and asked (now three times) if they could provide me with a supplier list for companies that service the KKL but the KKL sales person has not responded to my request. Very poor service attitude.
I'm visiting Lucerne from Australia for a travel industry conference at the KKL. I've spent hours Googling trying to find a TV or business equipment hire place in Lucerne but just can find anything. What should be a simple 15 minute task has consumed hours and hours so far.
But things might work out OK now. The website linkes provided above have been great. I've sent off three inquiries. I'll see if any of them can supply a screen.