Instead of using Control-C, you can issue the kill command:
kill -KILLARG pid
For example
kill -15 1234
To get a listing of all available on your system, just do:
kill -l
That will return a list something like this:
1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL
5) SIGTRAP 6) SIGABRT 7) SIGEMT 8) SIGFPE
9) SIGKILL 10) SIGBUS 11) SIGSEGV 12) SIGSYS
13) SIGPIPE 14) SIGALRM 15) SIGTERM 16) SIGURG
17) SIGSTOP 18) SIGTSTP 19) SIGCONT 20) SIGCHLD
21) SIGTTIN 22) SIGTTOU 23) SIGIO 24) SIGXCPU
25) SIGXFSZ 26) SIGVTALRM 27) SIGPROF 28) SIGWINCH
29) SIGINFO 30) SIGUSR1 31) SIGUSR2
By default, if you don't specify the name/number, kill will use 15 (SIGTERM). It's basically a nice way of telling the process to terminate. If you're feeling particularly uncaring, you can use 9 (SIGKILL), which effectively bypasses the process altogether and tells the kernel to force the process to die. Control C is effectively sending 2 (SIGINT) to the process. It's a bit more complex, as Control C sends the SIGINT to all of the processes in the process group controlled by the program; however, for p2pool, it's effectively the same since there's only a single process.
Thank you very much, jonnybravo0311. Intelligent, pointed, and useful verbosity at it's best. I'll spend some time going over the man for kill, now that you've pointed me in that direction.