Installing Roundcube webmail on multiuser

[webguyz]

Setting up a separate mail server on a multiuser network. Do I install Roundcube on the mail server or where the ISP manager is. In my case the ISP manager is a separate server. It probably makes more sense to put it on the mail server since I may want to add more mail servers down the road.

How would my mail clients use the webmail?

www.mail01.acme.com/webmail
www.mail02.acme.com/webmail

Is there a way to alias the /webmail and have it go to roundcube so if user bob@test.com wants to check email he goes to his domain www.test.com/webmail and it takes him to his roundcube webmail, whichever mail server that happens to be?

Thanks!