I've written this to be placed in the Remotes section, not Aliases. If you want to put it in Aliases, remove the word alias from the first line.
alias othernet {
.scon -at1 checknet othernet
if %othernet {
.server -m othernet
}
}
alias -l checknet {
if $network == $1 {
set %othernet $false
}
return
}
Of course, the actual details will vary and you'll have to put in the correct details in the various locations.