By MacBook do you mean one of the older polycarbonate ones?
I've done it in a 2010 13" MacBook Pro easily enough just had to get a OptiBay mounting kit to remove the DVD drive and slot the SSD in there. IIRC there were issues getting the SSD to be recognised by the SATA cable where the original drive was, but that might have just been me.
Strangely I have just done this on a MacBook (aluminum, late 2008) model. Was very straightforward to be honest. I did use the instructions on the Apple web-site as I am not very familiar with Macs. Incidentally I also upgraded the RAM and battery and I am impressed that a nearly six-year old laptop runs smoothly and quickly.
Mine was an OCZ Vertex 3. It was great. I think the issue I had with the SATA port was that only the Optical drive bay port was SATA 3 compatible whereas the HDD port was SATA 2, and back then there were performance issues with running SATA 3 SSD's on SATA 2 ports....from memory.