I am familiar with the Mid 2011 iMacs, which are in the same generation as yours.
Although, I forget if there is a third SATA port on the logic board of the Late 2009 iMacs.
Either way, there are options out there, and you don't necessarily need a kite and some kits are expensive, but kits sometimes makes things easier.
Do you want to keep the ODD? If not, one option is to use the SATA data connector of the ODD for the HDD and use the HDD SATA data connector for the SSD.
Actually, I can't remember if the Late 2009 iMacs had SATAII or SATAIII for the HDD, if just SATAII, then no need to switch the data cables, just use this adapter for the ODD:
OWC Data Doubler Optical Bay Hard Drive/SSD Mounting Solution for iMac 2009-2011.
www.amazon.com
Super easy switch.
Even if the HDD is SATAIII, you can still make the switch, but the ODD is only SATAII.
There are other options as well, just depending on what you want to do.