Do you consider the following to be an example of write access to the terminal?:
ssh -t -t -p 12345 firstname.lastname@example.org 'command1; command2;'
If so then you can do that with phpseclib's pure PHP SSH implementation. eg.
$ssh = new Net_SSH2(...); $ssh->login(..., ...); $ssh->exec('command1; command2;');
If not then (1) I'd say you'd be better off using phpseclib than you are with you're current implementation and (2) if you want what the phpseclib author has referred to as "interactive" support maybe you could try contacting the author? Maybe offer to pay him some money to incentivize him to develop the feature. Looking at the support forums the author seems responsive enough.