Can you explain more about what you want to do? There are lots of problems. For one thing, although the Humax can (locally) play a file that is still being recorded (ie "chase play"), the file is encrypted and being passed through the decrypt on the way to the HDMI output (or analogue conversion to SCART).
In order to access a decrypted file, we need to pass it through the DLNA server decryption path - which so far has needed the recording to be allocated a DLNA index (the nnnn.ts form of the file name) so it can be accessed through port 9000. Unfortunately the indexer only does its job after the recording has been completed.
Presuming all those things can be side-stepped, the next problem is real-time bandwidth. I forget what I worked out the bit rate required for StDef, but it's probably 2.5mbps or there abouts. HiDef is 12mbps. What upload data rate does your ISP give you?
There is a way around all these things: it's called Slingbox.