If power is not available at the 3410, use a power inserter at the bottom of the first 50' coax just before splitter #2:
Code:
20' > tv
/
C2 > 5' > SPLITTER #1 50' > TV
\ PCT-MPI-1G /
CM3410 > 50' > POWER > SPLITTER #2
INSERTER | 20' > TV
| /
SPLITTER #3
\
20' > TV
ALL SPLITTERS ARE 2-WAY