This can only be achieved in Linux.
Bitcoin/Altcoin wallet syncing is hard disk i/o intensive; specifically it requires fast seek times. But hard drive are bad in exactly that. As a result, your Internet connection is not the bottleneck for syncing, but your slow HDD seek times are.
This's apparent even if you've downloaded the block chain and reindexing it.
If you don't plan to buy an SDD for syncing your wallets, it's possible to sync equally fast with a Pendrive or flash disk instead.
First format the flash disk in a flash oriented file system like Nilfs (vfat and NTFS are the slowest file systems available). Now mount it and take a note of the mount point (I call it X)
As you might have known, the altcoin/Bitcoin wallet creates a directory named .[coin name] in your home directory where it downloads the block chain, and stores other relevant information like wallet.dat, transactions, block index, logs etc... For Bitcoin it's .bitcoin, for Litecoin it's .litecoin. It's different for every alcoin, often the coin name. In my e.g. I'll call the directory Z.
Now you got 2 options.
First option --
Copy this directory to X. Lets call the copied over directory Y. Delete the contents of Z (which resides in the home directory).
Now you need to use the mount --bind command as such --
mount --bind [path to directory Y] [path to directory Z]
Restart wallet and see the speed of your sync.
Second option --
Move Z to X. Symlink Z to your home directory either using the ln command or your file manager.
And you're done! Now you can quickly sync.
I'll make an nilfs tutorial which will help you further to sync faster.