You probably can, but using the log splitter to control a winch, just don't know how the winch will work in reverse, as the relief on the retract on the log splitter will activate and stop the winch and return the lever to neutral.
Using this diverter/selector valve, the log splitter pump would provide the source for the log splitter valve, and if no power is selected, the diverter valve would would send fluid to the log splitter cyl, and with 12v selected , the control valve would send fluid to a hyd motor for the winch.
Surplus Center - SAE 12 15 GPM DOUBLE SELECTOR VALVE 12VDC P15438-2
http://www.surpluscenter.com/Instruct/I9-7738-A.pdf
Why not add a single spool valve , with float, to a log splitter valve with PB, and be done with it.
3 ed option. This valve might be a better option all in one valve. The first spool is a log splitter valve, and the second spool is for a log lift, but instead of a log lift, add the winch hyd motor to this spool.
Surplus Center - 2 SPOOL 25 GPM PRINCE LOG SPLITTER/LIFTER VALVE
4 th option. Use the two lever auto spool with PB,
http://www.surpluscenter.com/item.asp?item=9-6587-PB&catname=hydraulic
and use this valve below as the winch and log lift. Use the float spool with the winch, as you can freewheel the winch in float. The other spool would be a log lift.
Surplus Center - 2 SPOOL 8 GPM PRINCE MB21GB5C1 DA VALVE W/FLOAT
Need to match up the hyd flow through all the valves.
So,if you have the money, the auto log splitter valve will do a auto split operation as you get the next log ready for either winching, or log lifting.
You can't do both at the same time, as the auto-valve will take all the fluid to split, as soon as the cycle is done, then you can winch or log lift.
