The concerned ebuild although it installs html documentation does not put arch.ps file in /usr/share/doc/tla-1.1 This can be achieved by adding lines: cd .. docinto ps dodoc ps/*.ps just after the line dohtml -r . in src_install function. Best Regards.
The latest stable ebuild 1.2-r2 installs ps files. Thanx for the report though and sorry for the delay.