Fanuc M3 drip feed

A while back I bought a Yuasa CNC mill with a Fanuc M3 control. I'd
like to find a way to drip feed large programs from a PC. I've heard
different ways which include changing some of the mainboard chips, or
buying a behind the tape reader, but I think there should be some way
to communicate directly with a PC. I found a diagram in the electric
circuit diagram manual. (I'm glad that came with it, even if this
info doesn't help) The connector labeled RS-232 into the control
(not the cable from the reader) has the following pinout:
1-FG (GROUND)
2-SD
3-RD
4-RS
5-CS
6-DR
7-SG
8-CD
14-TTY3
16-TTY2
17-TTY1
20-ER
25-+24v

The cable from the reader itself is as follows:
1-FG
2-SD
3-RD
6-DR
7-SG
11-RDY
U10-200A
V10-200B
G-G
I don't have a clue what the last three are, but they're in the same
diagram. There's also some info on connecting an ASR33 teletype but
I didn't think that would be relative. Am I wrong in thinking this
is a standard RS232 connection that should plug straight into a PC if
I cut out the +24V wire? What could happen if I tried it?
Thanks in advance for any help on this.
Nate