NOTE: See (also) a corrected/improved answer in the question itself.
Following solution worked for me:
Open a terminal and backup com.apple.dynamic_pager.plist which you're going to change in a second:
$ cd /System/Library/LaunchDaemons
$ sudo cp com.apple.dynamic_pager.plist{,_bak}
convert binary plist to xml:
$ sudo plutil -convert xml1 com.apple.dynamic_pager.plist
and open it with your favorite text editor
$ sudo vim com.apple.dynamic_pager.plist
it'll look something like this:
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
3 <plist version="1.0">
4 <dict>
5 <key>EnableTransactions</key>
6 <true/>
7 <key>HopefullyExitsLast</key>
8 <true/>
9 <key>Label</key>
10 <string>com.apple.dynamic_pager</string>
11 <key>OnDemand</key>
12 <false/>
13 <key>ProgramArguments</key>
14 <array>
15 <string>/sbin/dynamic_pager</string>
16 <string>-F</string>
17 <string>/private/var/vm/swapfile</string>
18 </array>
19 </dict>
20 </plist>
In line 17 modify /private/var/vm/swapfile (e.g. /Volumes/partition2/swapfile), save and close your editor (":x" will do both in vim).
convert the plist file back to binary:
$ sudo plutil -convert binary1 com.apple.dynamic_pager.plist
After rebooting your Mac you should find the swapfiles in the directory you specified.
If you run into any problems you can restore the backup you created in the first step with:
$ cd /System/Library/LaunchDaemons
$ sudo cp com.apple.dynamic_pager.plist{_bak,}
Why don't you just get an eSATA bracket and pull it to one of the SATA connectors in your Mac Pro? Much more elegant, much better, and no need to worry about driver support.
If you really must have an eSATA PCI-E card for any reason... then good recommendations are from FirmTek (which doesn't use the Sil3132 chipset). Firmtek, who writes their own drivers, have pledged support for 10.6.
Best Answer
I go to macports.org official site and search for mplayer inside available ports. I see there are two packages:
mplayer
cannot be installed on 10.6.x butmplayer-devel
can. I installed it and be able to do all of the operation. Thanks you guy for sharing.