documentclass[a4paper,10pt]{article}
usepackage[T1]{fontenc}
usepackage[utf8]{inputenc}
usepackage[english]{babel}
usepackage{csquotes}
usepackage{filecontents}
begin{filecontents}{jobname.bib}
@article{greenwade93,
    author  = "George D. Greenwade and A. Author and B. Buthor and C. Cuthor",
    title   = "The {C}omprehensive {T}ex {A}rchive {N}etwork",
    year    = "1993",
    journal = "TUGBoat",
    volume  = "14",
    number  = "3",
    pages   = "342--351"
}
end{filecontents}
usepackage[backend=biber,style=alphabetic,maxnames=10]{biblatex}
addbibresource{jobname.bib}
DeclareLabelalphaTemplate{
 labelelement{
  field[final]{shorthand}
  field{label}
  field[strwidth=2,strside=left,ifnames=1]{labelname}
  field[strwidth=1,strside=left]{labelname}
}
% labelelement{
%  field[strwidth=2,strside=right]{year}
% }
}
DeclareFieldFormat{extraalpha}{#1}
DeclareFieldFormat*{title}{mkbibemph{#1}}
begin{document}
cite{greenwade93}
printbibliography[heading=bibintoc]
end{document}