You intent to re-encode your film to mask the text ? The result will be awfull.
Better to find an other source without the subtitles, or to live with them.
Not saying that we are dealing with MPEG2 so unless you plan to use virtualdub to frame serve tmgenc, you are definitely not going on the good path. If I remember well there is a version of delogo for avisynth, you should better use it.
Look at there :
http://www.kvcd.net/forum/viewtopic.php?t=10918
Note: delogo is aimed to remove a logo, that is a static pattern. To remove subtitles, it does not work very well. I'm not sure about what you call "text".