Very simple plugin to change the map via console commands (it uses the ForceChangeLevel() sourcemod function). I post here because this is nothing more than a list of commands.
I'm lazy and dislike typing in the command and map name, so now I type in the numbers related to the map.
For example to change map to:
c1m1_hotel -> 11
c3m3_shantytown -> 33
c10m2_drainage -> 102
c11m5_runway -> 115
So as you can see c1m1 becomes 11, c3m3 is 33, c11m5 is 115... The rest you should be able to work out.
EDIT: Added support for L4D1:
1. No Mercy
2. Crash Course
3. Death Toll
4. Dead Air
5. Blood Harvest
6. Sacrifice
So 63 would load finale of Sacrifice, or v31 to load versus death toll 1st chapter.