Can't you wait for a gap, @Rita2164? I wouldn't be overly impressed to swallow this as a guest, but if you have long-term ones, where there's more of a relationship, throw in a sweetener - chocs/bottle of wine etc?
@Rita2164 It depends on how much inconvenience, are we talking a drop off or an installation, if installation, how much time would it take? If it is something that could be done while the guests are out for the day, it might be do-able. But, I think you should probably wait until there is a gap, since you're introducing a huge variable...installation may not go as planned, work crew could be messy/loud, etc. etc. and this would reasonably upset guests.