You can't really remove the limit, as it works by allocating enough memory for that long a recording, but you can increase (or decrease, if you really want to) the amount of recording time it gives you. Now, you can't go crazy and set it to 9,999,999,999 seconds or something, as you need to have enough memory. (Audacity gets away with this by recording to the hard drive.) 5 minutes, however, is more than enough for most purposes.
(If you're using XVI32, skip the next paragraph.)
First, you're gonna need to convert that to seconds. 5 × 60 = 300 seconds, or 0x12C. Inside the EXE, the limit is stored as a 4-byte long value. You may think that as 4 bytes would be 00 00 01 2C, but the bytes are reversed. Instead, it's 2C 01 00 00. It's confusing, I know, but it's just the way it is.
Anyway, make a copy of Sound Recorder, and open the copy in your hex editor. The limit is stored at address 0x628E, so goto (in XVI32, it's Address>Goto...) that address. Follow the instructions below:
If you're using XVI32:
- Go to Tools->Encode number...
- Type 300 (or however many seconds) in the text box.
- Select "longint (4 bytes)" on the left.
- Select "Overwrite at current adress [sic]" on the right.
- Click OK.
- Switch to Overwrite mode if necessary, usually using the Insert key. You should be able to tell which mode you're in by looking at the status bar. It should say either Insert (INS) or Overwrite (OVR).
- Type in the four bytes you calculated above, such as 2C 01 00 00.