I believe the only way to do this requires setting the recording service to logon as a specific user (and I think the username/password must match on both machines - right?) and manually edit the config.xml to point to the UNC network path
such as
\\192.168.0.77\d$\working
which is how I just set it up on my network for testing. and it recorded to my other pc's hard drive.
MAIN RIG - Opteron 165 @2900MHz
2x1024 OCZ Platinum @ 480MHz (3.3.3.7)
HTPC - Athlon 64 3800+
2x512 Corsair XMS C2
ATI Theatre Pro 550 - MCE Blaster - Comcast Set Top Box
Hauppauge HVR-2250
one thing to be sure of is that your network is up to the task, otherwise you will have problems. as long as you can sustain transfer rates that are higher than the bitrate (leaving room for network overhead) of the files you record.
such as, I record at VBR of 5.5 - 9MB/s which translates (roughly) to between 45 and 72 megabits per second. On a 100Mbps network, this could be an issue if the network hardware were not up to the task.. But I have gigabit lan thoughout my house, so I have plenty of room for the traffic.
There are free programs you can download to test your traffic (not the simplest to use, but pretty self-explanatory). If you wanted to be sure your network was suitable.
I use iperf. A google search should find it, it runs from a command prompt.
MAIN RIG - Opteron 165 @2900MHz
2x1024 OCZ Platinum @ 480MHz (3.3.3.7)
HTPC - Athlon 64 3800+
2x512 Corsair XMS C2
ATI Theatre Pro 550 - MCE Blaster - Comcast Set Top Box
Hauppauge HVR-2250