Intell, I'm not sure how much a testimonial is worth over the internet, but I swear to you - I have a late 2008 MacBook, first generation unibody.
Less than one week ago I put an unformatted SSD into my machine and command+r booted to the recovery menu. I successfully loaded Yosemite onto the computer after formatting the SSD *without* using an install disc or bootable USB stick. My Time Machine external hard drive was connected to my computer at the time, so perhaps it pulled the OS from there, but if it did, it was transparent to me. If that's the case, then it should work the same way for mike0000, who has a time machine backup available.
mike0000, I had opted for the clean OS install option in case it was the Yosemite beta that caused issues with my old HDD. To be honest I expected that it was going to reinstall Mavericks, so maybe it did just pull the OS from my time machine backup (in which case I just did in two steps what you should be able to do in one).
EDIT: this disclaimer appears on the support page linked by Intell: "Some computers that did not come with OS X Lion or later installed can use the OS X Internet Recovery feature after applying a firmware update." It's likely that I had previously done this update back when I was upgrading my machine in advance of installing 8GB ram (which wasn't originally supported on the 2008 unibody macbook) but became supported later. So mike0000, your mileage may vary. If you don't think you've installed any firmware upgrades from Apple, you may want to try it the old fashioned way as Intell suggested.