documentclass{article}
usepackage[LGR,T1]{fontenc}

DeclareSymbolFont{custom}{LGR}{bodoni}{m}{it}

newcommand*{msym}[2]{DeclareMathSymbol{#1}{mathalpha}{custom}{#2}}

msym{alpha}{"61}
msym{beta}{"62}
msym{gamma}{"67}
msym{delta}{"64}
msym{epsilon}{"65}
msym{zeta}{"7A}
msym{eta}{"68}
msym{theta}{"6A}
msym{iota}{"69}
msym{kappa}{"6B}
msym{lambda}{"6C}
msym{mu}{"6D}
msym{nu}{"6E}
msym{xi}{"78}
msym{omicron}{"6F}
msym{pi}{"70}
msym{rho}{"72}
msym{sigma}{"73}
msym{tau}{"74}
msym{upsilon}{"75}
msym{phi}{"66}
msym{chi}{"71}
msym{psi}{"79}
msym{omega}{"77}
msym{varsigma}{"63}

newcommand*{mylgralphabet}{alphabetagammadelta
epsilonzetaetathetaiotakappalambdamunuxi(o)
pirhosigmatauupsilonphichipsiomegavarsigma}

begin{document}

{mathversion{normal}$mylgralphabet - (normal)$}

{mathversion{bold}$mylgralphabet - (bold)$}

end{document}