Command name aliases can be constructed using the Tcl interp command:
XSPEC> interp alias {} <command_alias> {} <xspec_command>
where <xspec_command> is the name of the command for which you wish to make an alias, and <command_alias> is the name of the alias you wish to set for the command. The {} are required syntax.
To delete the alias <command_alias> use the following:
XSPEC> interp alias {} <command_alias> {}