how to transfer 24-bit data through 8-bit spi

Hello everyone.I am working on a project to develop frequency synthesizer(LMX2595). In this I need to program the frequency synthesizer IC by SPI protocol. For this I have selected MSP430F5529 micro controller to program the synthesizer IC (LMX2595). I am facing difficuty in developing code for the micro controller. I need to operate the micro controller in master mode and transfer data to the slave device (LMX2595 synthesizer IC). Generally I have 24-bit data to be transferred of about 79 registers, But the available SPI in micro controller (MSP430F5529) is 8-bit. The 24-bit data format is 1-bit R/W, 7-bit Address, 16-bit data. I took the sample example code and modified but, I am facing error with respect to the write function. Generally I have split the 24-bit data into 3 Bytes, later by running for loop I have transferred the 24-bit data. I really don’t have much time, Any help with respect to programming point of view will be greatly appreciated.

Thanks in advance