The short answer is No, not easily (or cheaply).
From the IBM Thinkpad X20 User's Reference:
"If you forget your power-on password, you cannot reset it. You must take the computer to an IBM reseller or IBM marketing representative to have the password canceled."
"If you forget your hard-disk password, there is no way to reset your password or recover data from the hard disk. You must take your computer to an IBM reseller or marketing representative to
replace the hard disk drive. A fee will be charged for parts and service."
"If you forget your supervisor password, there is no way to reset it. You must take your computer to an IBM reseller or marketing
representative to replace the system board. A fee will be charged for parts and service."
Your only other option would be something along the lines of this:
http://www.pwcrack.com/security_chips.shtml
NOTE: This type of option requires you to remove the security chip that is currently soldered to the laptop's motherboard and solder in a new one.