This isn't a question about logistics of doing so, it's about rules: If a team decided — in a high-stakes, last 30 seconds game — to have a second goalie secure an 'outer perimeter'- or maybe a particular half [to prevent accidental screening], after pulling a player to do so, is this explicitly disallowed?
The 2012-2013 National Hockey League (NHL) rules state:
Section 2, Rule 5.3
Each team shall be allowed one goalkeeper on the ice at one time.
The rules do not explicitly disallow two goaltenders on the rink at one time.
However, the rules do implicitly allow two goaltenders on the rink at one time, but this is in regard to line changes.
Section 10, Rule 82.1
Goalkeepers’ substitution during a game will be conducted within the same time frame as a regular line change (per Section 10, Rule 82.2 - 5 seconds for visiting team, 8 seconds for home team). No extra time will be allotted to the goalkeeper coming off the bench, except in the case where an injury to a goalkeeper occurs.
So, the scenario you state would not be covered in the cited rules above, but two goalkeepers can be on the ice at one given time during the course of a line change.