Here are the steps I find:

the commands I run are: (note you have to run cmd.exe as Administrator, do this only if u know what your doing)

mklink /J "C:\Program Files (x86)\Sc2\Versions\Base21029" "F:\other\scdata\Base21029"

Also for kicks I tested the battle.net folder out too (it seems to do with the UI of battlenet):

mklink /J "C:\Program Files (x86)\Sc2\Battle.net" "F:\other\scdata\battle.net"

since its only an extra 100 meg to load

And for the .exe file:

mklink "C:\Program Files (x86)\Sc2\StarCraft II.exe" "F:\other\scdata\StarCraft II.exe"

this creates Junctions/links to the original location on my C: while the actual files are located on F: (my ram-disk)

http://www.teamliquid.net/forum/viewmessage.php?topic_id=332536

I plan to use this ramdisk because I saw a review, seem like this one has the best speed out of free ramdisk softwares:
http://memory.dataram.com/products-and-services/software/ramdisk

I have only 4fb rams with xp 32 bits so actually 3.3 gb in my running windows xp, I check those folders and files are less than 200mb, so I would create a ramdisk with 200mb.