In Winrunner, the password is recorded in the encrypted form but in SilkTest it is recorded as it is.
Can't be done right within the script, but if you want to make a work around, you could read it from a file.
If that's not good enough (the password would be stored in the file in plain text too), you could use a tool to encrypt the password and use that tool to decrypt it.
You could then make a call to an external language (Ruby, Perl, Python, etc.) to do the heavy work of encrypting and decrypting the information and pass that through as a variable.
The problem is that whatever method you use to enter the password unencrypted into the login screen can also be used to just write it to a file.
Don't use your own account. Use a dummy, testing account.