If I read Ferfer request.....I believe he wants to be able to start a recording, Later than when it actually starts, and end Earlier that when it actually ends....One guess for this is that maybe he wants to DVR record another show that starts at the same time and a 2 record DVR may have a "same time" conflict. The 2 shows may not be able to be recorded, because the 1 or 2nd show that is already being record, will conflict with the next show....thus not get recorded.. I've run into this problem myself. Some live shows start and stop just slightly past the whole half hour or full hour time frame. The overage conflict that overage with the next show that you want to record, especially if the next recorded show is on a different channel. If its on the same channel just following the previous, there is no problem....just when its on another station. On my system, because I have a 2nd Contour2 DVR, I just find the conflict show just ends up being recorded on the other DVR instead of the primary DVR.
For my sports, well the ending running over is more important. I usually record 30, 60 or even 90 over. You can always just set the DVR to record the next show that follows the sports show.