Xmit through MSComm

Does anyone know how I can format a Single Data Type number into a buffer so it can be transmitted as a 4 byte floating point number through MSComm?

i.e. Someting like:

Num1 = 3.14159
txBuffer(0) = ?
txBuffer(1) = ?
txBuffer(2) = ?
txBuffer(3) = ?
MSComm.Output = txBuffer

Thanks in advance!